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作者：Anonymous 在 罕见奇谈 发贴, 来自 http://www.hjclub.org
Sorry for the length, but I received it as a private mail, no link
Paternal Provisioning
versus Mate-Seeking
in Human Populations
Prof. Edward M. Miller
Abstract
Paternal investment theory suggests that in cold climates males were
selected for provisioning, rather than for mating success. In warm
climates, where female gathering made male provisioning unessential,
selection was for mating success. Male hunted meat was essential for
female winter survival. Genes that encouraged mating success were
selected for in warm (was cold) climates. Negroids (blacks) evolved in
warm cold climates, while Caucasians (whites) and Mongoloids (Asians)
evolved in colder climates. Mating is assisted by a strong sex drive,
aggression, dominance, sociability, extraversion, impulsiveness,
sensation seeking, and high testosterone. Provisioning is assisted by
anxiety, altruism, empathy, behavioral restraint, gratification delay,
and a long life span. Explanations are offered for racial differences in
many personality characteristics, hormone levels, monamine oxidase
levels, testosterone levels, lactase dehydrogenase metabolic paths, life
spans, prostate cancer rates, hypertension, genital (penis and testes)
size, vocal frequencies, liver size, muscle structure, mesomorphy, bone
density, sports performance, crime rates, rape, child abuse, earnings,
age at first sexual activity, AIDs, illegitimacy, divorce, marriage, and
polygyny rates. Eye color correlations are discussed. Negro family
structure in the Caribbean and the U.S. may reflect selection in Africa
during hunter-gather times. Comparison is made with differential K theory
and father absence theories.
Key words: race, climate, evolution, personality, polygyny, aggression,
provisioning, mating, dominance seeking, paternal investment
Rushton (1985, 1987, 1988, 1989b, in press) and Ellis (1987) have drawn
attention to the existence of many racial differences, including
behavioral ones, and shown that they were frequently arranged in the
order Mongoloid, Caucasoid, Negroid (or Negroid, Caucasoid, Mongoloid,
depending on the trait). The differences Rushton drew attention to
include twinning rates, (Negroids first, Caucasoids second, Mongoloids
third), intelligence (Mongoloids first, Caucasoids second, Negroids
third), various differences in aggression, dominance seeking,
impulsivity, extraversion, sexual behavior, genital size (Negroids first,
Caucasoids second, Mongoloids last), extent of altruism, and behavioral
restraint (Mongoloids first, Caucasoids second, and Negroids last), and
timing of birth, menarche, birth of first child, and death (Negroids
earliest, Caucasoids second, Mongoloids last).
Rushton explains his observations by a version of r versus K selection
theory. The terms r and K come from population biology, where r is a
population's maximum growth rate, and K is the environment's carrying
capacity. K selected species have been selected for success at
competition with conspecifics. Species selected for fast reproduction
with low ability to compete are called r selected. Rushton extends the
idea to human populations. He argues that Negroids are the least K
selected among human populations, Mongoloids the most K selected, and
Caucasoids in between. This idea has produced considerable scientific (J.
Anderson, 1991; Flynn, 1989; Leslie, 1990; Lynn, 1989; Roberts & Gabor,
1990; Silverman, 1990; Weizmann, Wiener, Wiesenthal, & Ziegler, 1990;
Zuckerman, 1991; Miller, 1993) and popular controversy (Gross, 1990;
Pearson, 1991, Chap. 5; Lerner, 1992, pp. 139-147), to which Rushton
(1989a, 1990a, 1990b, Rushton & Ankney, 1993) has responded. Chisholm
(1993) has also applied life cycle theory to humans, arguing that early
experiences with the correlates of high death rates affects the
allocation between mating and parenting.
This paper will propose an alternative explanation to differential K
theory. Like differential K theory, it will be derived from a standard
biological theory, parental investment theory. In some species, males
devote more effort to seeking mating opportunities. In other species,
they devote more effort to assisting their offspring. In each species,
males evolve to use the strategy that most promotes their fitness. Which
strategy most promotes their fitness depends on the effect of paternal
investment on offspring survival and fitness, and on the opportunities
for obtaining reproductively successful additional matings (Katz &
Konner, 1981; Clutton-Brock, 1991). Likewise, within the same species
different populations have been selected for different positions on the
paternal investment versus mating effort continuum.
In humans, an especially important form of paternal investment is
provisioning, bringing the mother and child food. Offspring's benefit
from provisioning depends on climate. In warm climates, females typically
can gather enough food for themselves and their children. In cold
climates, hunting is required to survive winter, and females typically do
not hunt (other than for easily captured small game). Hence, offspring
survival requires male provisioning in cold climates. Thus, cold climate
males were selected to devote more efforts to provisioning, and less to
seeking matings. In warm climates, such male provisioning was not
essential, even if desirable. Thus, warm climate males who devoted more
efforts to seeking mating opportunities, and less to provisioning, left
more offspring. This theory can explain many of the known racial
differences.
Paternal investment theory's chief advantage is its specificity as to the
traits populations should exhibit. It makes specific testable predictions
(which are generally sustained) as to how cold-adapted populations and
tropical populations should behave. In contrast, Rushton's and Ellis's
differential K theories, after stating that Mongoloids are most K
selected, and Negroids least, are very vague as to why this is. They fail
to predict how other races (Malays, Australian aborigines, Polynesians,
etc), or populations within the major races, should differ (J. Anderson,
1991; Miller, 1993).
To limit this paper's length, a detailed treatment of the evidence for
the racial differences discussed will not be attempted. The reader can
find relevant references in Ellis (1987, p. 159) and in Rushton's papers
(especially 1987, p. 1019, 1989a, p. 9) and in Rushton's forthcoming book
(in press). The author has checked most of these. Although many of the
individual studies could be improved on, the racial differences do appear
to be as Rushton and Ellis depict them. Strong evidence as to whether
most racial differences in behavior are of environmental or genetic
origin is lacking. While cultural explanations have been proposed for
many of the behavioral differences, (but not for the morphological, or
biochemical ones), there is not space to discuss them here. Occasionally,
when new evidence has appeared since Rushton and Ellis wrote, it will be
noted.
This paper combines several generally accepted ideas from different
disciplines. It accepts the evidence from human behavior genetics that
most personality traits have an inherited component (for instance Eaves,
Eysenck & Martin, 1989; or Bouchard, Lykken, McGue, Segal, & Tellegen,
1990, or Rushton, in press, chap. 4). From biology and population
genetics, it takes natural selection. From physical anthropology, it
takes the theory that humans have been separated into races long enough
to have evolved somewhat different appearances, many of which can be
traced to climatic differences. From sociobiology, it takes the idea that
males differ in the extent to which they devote their efforts to mating
versus parenting, and that basic human behavior traits evolved during the
hunter-gatherer 99% of human history (Barash, 1977; E. Wilson, 1975). It
extends this by arguing that cold weather hunter-gatherers evolved into
Mongoloids and Caucasoids, and tropical African hunter-gatherers into
Negroids, and that differences in morphological and behavioral gene
frequencies can be explained by the climatic differences during
hunter-gatherer times.
MALE COMPETITION FOR MATING OPPORTUNITIES
In many species, much male behavior consists of competition for females
(Barash, 1977; Wilson, 1975; Trivers, 1972). This seems to be true of
humans. Standard sociobiology explains differences between human male and
female behavior by contrasting the male's ability to father children by
several females with the female's inability to have children by more than
one male at a time (Symons, 1979; Hrdy, 1981). Thus, men evolved to
exploit any impregnation opportunities that arise, while women direct
their copulations to males who are willing and able to invest in them and
their children.
Thus, in discussing male behavior across species, biologists argue that
males evolved a trade-off between paternal investment and mating efforts
that maximizes their inclusive fitness for that environment (Draper,
1989, pp. 149-150). The argument generalizes easily to explain
differences in male mating and paternal investment within a single
species, such as humans.
Under some conditions males leave more descendants by devoting more
energy to seeking copulations (an endeavor that often includes prestige
seeking), and relatively less to provisioning their offspring. In these
conditions, selection will be for such characteristics as high sex drive,
aggression, a mesomorphic body build, and large testes. In these
conditions females can raise children with only limited male
provisioning.
In other circumstances, males are selected for extensive provisioning of
their children. This normally implies less energy being devoted to
seeking matings for two reasons. First, energy and resources devoted to
seeking additional matings would be diverted from provisioning their
mates and children, thus reducing the number of surviving children.
Secondly, added matings would frequently produce children able to survive
only if resources were diverted from the father's other children. The net
gain in surviving offspring would be small, or even negative. The first
effect of devoting more energy to mating is to reduce total male
investment in offspring, while the second spreads it among more
offspring, reducing per capita investment.
I will argue that selection for male provisioning is especially common in
climates with cold winters, where large game hunting is required for
survival. Children of males who failed to provision would often not
survive the winter.
Physical anthropologists can explain many racial variations as climatic
adaptations (Baker, 1974; Coon, 1965, 1982; Krantz, 1980; Roberts, 1978).
For instance, in northern latitudes, winter ultraviolet radiation
intensity is low, and pale skin permits maximum vitamin D production. In
low latitudes, there is a risk of excess vitamin D production and
sunburn. Here dark skin is optimal (see Robins, 1991). Likewise,
variations in adult ability to tolerate lactose has been interpreted as
partially an adaption to low levels of ultraviolet radiation (Durham,
1991). Lynn (1991b) has contrasted the hunting required for survival in
cold climates, in which Mongoloids and Caucasoids evolved, with the
tropical gathering. He used this to explain the racial intelligence
differences he had earlier documented (Lynn, 1991a). Here, this
difference in reliance on hunting will be used to explain many other
behavioral differences.
The reader will probably have little difficulty in accepting that
Negroids evolved in the tropics, and Caucasoids and Mongoloids in colder
climates. However, some may wonder why the Mongoloids are considered to
have evolved in a colder climate than did the Caucasoids. One reason is
that certain Mongoloid features (a stocky body build, and distinctive eye
folds) appear to be adaptations to arctic conditions (Baker, 1974; Coon,
1965, 1982; Krantz, 1980; Roberts, 1978).
Admittedly, Europe is also cold. However, it is believed that farming
started in the Middle East and then spread with the farmers' migration
into Europe. This conclusion comes from archaeology and a northwest to
southeast distribution of certain genes (Menozzi, Piazza, &
Cavalli-Sforza, 1978; Piazza,1993; Sokal, Oden, & Wilson, 1991). The
latter suggests a population movement, rather than merely technology
diffusion. The result is that some European ancestors were Middle Eastern
hunter-gatherers, rather than hunter-gatherers who had evolved where the
populations now live.
Hunting as a Function of Latitude
Richard Lee (1968, pp. 42-43) in the widely cited Man the Hunter book
emphasized that most calories eaten among typical (tropical)
hunter-gatherers come from gathering, leaving the impression that
gathering was the primary subsistence mode for the ancestors of most
peoples. However, this really held only for the well studied inhabitants
of warm and tropical areas, which are the majority of surviving
hunter-gatherers. He reports that "In warm-temperature, sub-tropical, and
tropical latitudes, zero to thirty-nine degrees from the equator,
gathering is by far the dominant mode of subsistence, appearing as
primary in 25 of the 28 cases." He found that 6 of the 8 societies whose
latitude exceeded 60 degrees relied primarily on hunting. Eskimos
(Inuits) are classic examples. In cool to cold temperature latitudes,
from 40-59, degrees fishing was the most common subsistence mode.
Temperature tells the same story, "Hunting is primary in three of the
five societies in very cold climates (annual temperatures less than 32
F0..), fishing is primary in 10 of the 17 societies in cold climates
(32-50 F0.): and gathering is primary in 27 of 36 societies in mild to
hot climates (over 50 F0.)."
Fishing (usually male) appears to be a relatively recent development
(Washburn & Lancaster, 1968, p. 294). In earlier times, before the most
fertile mid-latitude lands were cleared for farming, there was probably
more mid-latitude hunting. The hunting of large sea mammals from boats,
so important to Eskimos, developed relatively recently.
Especially significant in the Lee tabulation (p. 43) is the absence of
any predominantly gathering society above 500 latitude. Gathering is the
primary way a single mother can feed her family.
The above tabulations suggest that ancestral Negroids relied on gathered
vegetable material and ancestral Caucasoids and Mongoloids relied on
animal matter from hunting and fishing. Supporting evidence is provided
by blacks' greater current salt retention compared to whites (Luft et
al.., 1991). Presumably, the lower salt content of the prehistoric low
meat African diet, combined with greater sweat loss, selected for salt
retention.
Another piece of evidence consistent with the environment of evolutionary
adaptation for Caucasoids involving more meat eating than Negroids'
original environment is that the Negroids' livers are smaller (Lewis,
1942, p. 276). The liver' s function is to produce bile, which is used in
fat digestion. A diet lower in fats (which are much more common in animal
foods) would requires less bile for digestion.
The obvious problems of hunting while pregnant or with a small child
assure that males do the hunting (for other than small and slow game) in
virtually all societies (Friedl, 1975, p. 16-18; Watanabe, 1968).*(1) In
climates typical of those now prevailing north of 500 a woman would have
difficulty raising children without male supplied meat.
An example of women hunting small game is provided by the Twi of Melville
Island, Australia (Goodale, 1971, pp. 151-169). They commonly hunt
lizards, snakes, crabs, rats, and opposum and bandicoot. The last two are
small animals found sleeping in logs or hollow trees, and typically are
easily killed where found (i.e. without pursuit). In northern climates
most such small animals would be hibernating during winter, or would be
rare then.
The Hadza of Tanzania are typical tropical hunter-gatherers. Woodburn
(1968, p. 52) describes the abundance of game and other food, stating,
"For a Hadza to die of hunger, or even to fail to satisfy his hunger for
more than a day or two, is almost inconceivable."
Barnard and Woodburn (1988) noted that, "In all known hunter-gatherer
societies, with immediate return systems, and in many but not all,
hunter-gatherer societies with delayed return systems, people are almost
always able to meet their nutritional needs very adequately without
working long hours." If gathering permits this, one would expect that
women could adequately feed themselves and their children without male
provisioning. Most tropical hunter-gatherer societies are immediate
return ones.
Gardner (1972, p. 414), in describing the Paliyans, a foraging people of
India, has pointed out that, "In normal times Paliyan men and women spend
a bare three to four hours a day obtaining food and evidence no anxiety
whatsoever about its supply." Single individuals are able to feed
themselves easily, and married couples may not feed each other. Male
provisioning is clearly not necessary. Not surprisingly, with the parties
not needing each other economically, "the usual situation is one of
fragile, often serial, unions, terminated quickly by the offended party
when conflict arises" (p. 419).
A similar impression is left by descriptions of other tropical
hunter-gatherer societies. Lee & DeVore's famous Man the Hunter is often
summarized as showing that most calories come from gathering, not
hunting, that most gathering is done by females, and that
hunter-gatherers need spend only a relatively small part of their time in
gathering. Taken together, these facts imply that a woman can feed her
family with little male assistance. This suggests that males would leave
more descendants by focusing their efforts on mating rather than on
provisioning.*(2)
The Cold Climate Situation
Now consider a cold climate, such as prevailed where the northeastern
Mongoloids (Chinese, Japanese, Koreans) are believed to have evolved.
Even now these areas have cold winters. During the last ice age they were
much colder. Their people's physical features evidence numerous cold
adaptations (Coon, 1965, 1982; Krantz, 1980; Roberts, 1978).
Although winter is only part of the year, it is the season animals have
the greatest difficulty surviving. Most plant foods disappear (fruits,
berries, edible leaves). Hunting becomes more difficult. Most animals
time their reproductive cycles so there are no winter young or eggs. Eggs
and young were the easiest animal protein for primitive men and women to
obtain, since they were immobile or moved too slowly to escape. Many
adult animals migrate (birds) or hibernate to escape the winter food
shortage. Frozen ground prevents humans from digging for tubers and ice
prevents or complicates fishing. Snow cover makes it hard to find fallen
nuts or tuber locations, and makes walking much more difficult (Jochim,
1976, p. 138). Winter has severe weather episodes in which it is unsafe
to leave shelter to hunt. Also, winter cold increases the body's food
requirements (Kleiber, 1961, p. 164, p. 239). Finally, winter is a time
of short days (Torrence, 1983, emphasizes this). Thus, the very period
when food is needed most is also when it is scarcest, hardest to acquire,
and the time for gathering it is least.
Admittedly, there could be geographical circumstances where winter is
easier. Many ungulates (such as elk) in mountainous areas winter in the
lowlands. Possibly this concentration, aided by ease of tracking in snow,
could make winter an easier time for survival. However, males would still
be expected to be the sex that took advantage of this situation.
Jochim (1976, pp. 141-143) has estimated food consumption for German
mesolithic foragers by seasons. Plants (female gatherable) are estimated
to be 30% for spring and summer, 23% for fall, but zero in winter.
In northern climates a female cannot be self supporting. A female would
avoid marriage to a hunter already supporting another's family. Even if
married to an excellent hunter, a second wife (receiving half of his
support) would probably be poorly provisioned. Cold climates lead to
environmental monogamy (Alexander, Hoogland, Howard, Noonan, and Sherman,
1979). Males evolve drives that encourage family provisioning, and
discourage competing for mates.
Large game hunting often requires cooperation by groups of males. A male
who doesn't have the cooperation of others is likely to bring home less
meat, and to leave fewer descendants. Variability in hunting success
makes it desirable to hunt in groups that share their kills. Withdrawal
of cooperation by other males is a likely penalty for trying to
impregnate another's wife. In such circumstances, the drives that lead to
seeking multiple mates are selected against.
Of course, in a warm climate hunting groups are likely to exist and a
philandering male may be penalized by exclusion from the group, or less
cooperation. However, with opportunities for gathering and hunting small
game abundant at all times, the penalty of loss of participation in the
large hunts is less severe, and the selection against mating drives
weaker.
Why presume that primitive hunters could not kill enough food to carry
multiple females through the winter? After all, there is a lot of meat on
even a single ungulate carcass. If game were abundant enough for a
typical hunter to support more than one wife, population would grow. It
would grow until the pressure on the game resource had reduced the yield
from hunting to where one hunter could typically support only a single
wife and offspring. The argument is the standard Malthusian one.
Although Man The Hunter is usually cited as showing that hunter-gatherers
can feed themselves with a short work day, this appears true only of the
tropical peoples discussed. That book also contains Balikci's (1968, p.
82) discussion of the Netsilik Eskimos, who had a 10% loss of life from
starvation in two years. The inland Eskimos appear to be able to support
only one family per male (Alexander et al., 1979). Other northern
hunter-gatherers such as the Ainu appear to have monogamy as the typical
pattern, even if a few males have more than one wife.
Other descriptions of northern hunting peoples emphasize the difficulty
of the life and the risks of starvation. For instance, Rogers (1972, p.
104) in his discussion of the Mistassini Cree, American sub-Arctic
natives, states that, "Securing sufficient food is a constant problem and
a never ending concern. Times of starvation are vividly remembered." He
also states that the gathering of vegetable foods is minimal. In such an
environment a typical male could not support more than a single female.
Any inadequate provisioning of her offspring could reduce his
reproductive success.
Likewise, Nelson (1973) discusses how those Kutchin (north Alaska) who
remembered the old ways emphasized hardships and lack of food. He reports
that similar attitudes to the past are found among other Athapaskan
people. Emphasis is placed on far north people because Ice Age Europe and
Asia had climates similar to these peoples' current homes (Soffer &
Gamble, 1989; Scott, 1984).
Admittedly, a female without a "husband" would probably receive some meat
from brothers, other family members, and other band members. In
contemporary hunting bands game is usually shared with other band members
(Hawkes, 1993). Even unmated females get some. Such a meat sharing system
is very useful in spreading the risks of the hunt among families (Hames,
1990). In the short run, this clearly supplies some meat to women without
husbands. However, it is likely that in the long run a female unattached
to a male hunter would suffer. Adverse effects are most likely during
occasional famines, when social traditions of sharing are likely to break
down. Then band members are likely to give priority to their own
offspring. One possible mechanism is through the more successful hunters
joining bands with fewer non-related dependents, where their own families
would be better provisioned. Thus, in time of famine, poor provisioning
by a father would affect his children's survival. The sharing systems
observed among current hunters probably evolved relatively late, after an
earlier system in which males gave priority to themselves and their
families. While sharing may moderate regional differences in the
consequences for offspring survival of male provisioning, they are
unlikely to eliminate them.
Predictions of the Hypothesis
There appear to be several traits that contribute to success in mating
competition. A strong sex drive would lead to more matings. A strong
Coolidge effect (in which women other than regular sex partners were
considered unusually attractive, see Symons, 1979, p. 209) would
encourage taking additional wives, matings with other men's wives, and
rape. Efforts to mate with other men's wives involves risks of
retaliation. Thus, aggressiveness, impulsiveness, and lack of fear would
contribute to leaving more descendants. If one were to have only an
occasional mating with certain women, greater sperm production would lead
to leaving more children. If males frequently succeeded in mating
another's wife, a high sperm production and strong sex drive would lead
to leaving more offspring.
Empathy with others is not conducive to extra-marital relationships or
even to taking additional wives. For instance, strong sympathy for one's
children is likely to lead to devoting spare resources to them, rather
than using the resources to purchase sexual access through prostitutes,
concubines, or extra wives. Likewise, if extramarital intercourse
violates social mores, a strong tendency to follow social mores is not
conducive to extra-marital access.
The above paternal investment theory makes a number of interesting
predictions about the mating patterns of hunter-gatherer populations in
warm versus cold climates.
Using Racial Data to Test Clinal Theories
Because agriculture was adopted relatively recently, differences that
emerged during the hunter-gatherer stage should have survived into the
ethnographic present. The above suggests that personality and behavior
differences among modern populations should be correlated with the winter
temperatures where they evolved. Tropical populations would be selected
for greater mating efforts and lower paternal investment. In cold
climates, the opposite would be true.
Ideally, analysis would use data expressed as behavioral clines drawn
from data on many different populations. (A cline is a line connecting
points of equal values for observations, such as lines on a weather map.)
Unfortunately, such data is rare. Admittedly, some data is available from
physical anthropologists' studies of specific populations, and from the
ethnographic record, coded in the Ethnographic Atlas (Murdock, 1967).
However, some population level studies do exist using such data. Wolfe
and Gray (1982) found a correlation between the extent of polygyny and
the height of males and females. This is easily explained by the taller
males having an advantage in acquiring mates, which leads to greater
selection for height in polygynous societies. Wolfe and Gray were
surprized not to find clear evidence of greater sexual dimorphism is such
societies, which they expected from the animal evidence. However, in
humans it is known that most genes that affect height appear to affect
both males and females equally (excluding the obvious exception of those
carried on the X or Y chromosomes). What they regarded as a puzzling
correlation between polygyny and female height is easily explained. If
taller males leave more offspring, the mean height of both males and
females will be raised, leaving sexual dimorphism little changed.
Wolfe and Gray used a code for the extent of father-infant proximity in
the first year of life as a measure of male parental investment. They
found that this correlated to a statistically significant degree with
measures of polygyny (Table 8.1), and with male and female heights. Since
it is unlikely that height causes differences in marriage patterns, it is
more plausible that sexual selection has affected the frequencies of
genes for height, and possibly for a measure of paternal investment (if
that is subject to genetic variability). For these effects to have
appeared, the differences in marriage patterns must have persisted long
enough for natural selection to have acted. Although Wolfe and Gray did
not notice this, this is the first clear evidence that sexual selection
has played a role in the evolution of differences in gene frequencies
among human populations.
Studies of the above type can be done for only a few variables. As Wolfe
and Gray (1982, pp. 206-207) report, "Our search of the literature of
cross-cultural codes revealed no codes that directly rate societies on
the degree of male parental investment. This lack of codes is partly due
to the fact that ethnographers rarely had a theoretical orientation in
which the problem of male parental investment was of central concern and
therefore rarely collected data on this problem."
However, various physical variables do correlate with climate, among
which are skin color, shape of nose, body mass and shape, etc. These
highly visible surface features include the variables usually used for
racial classification. It appears that Negroids evolved in the warmest
climate (tropical Africa), Mongoloids in the coldest (the North
China-Siberia area), and Caucasoids in intermediate climates (Europe and
the Middle East). These areas are separated from each other by barriers
to gene flow. The Sahara partially isolates tropical Africa. During the
ice ages, the Himalayan ice sheet separated the Caucasoids from the
Mongoloids.
Limits on gene flow between different areas (although not complete)
permitted populations in each region to develop somewhat different
morphology and behaviors. Each evolved in their respective environments
so as to produce the largest numbers of descendants. Each of the major
races of mankind, Negroid, Caucasoid, and Mongoloid, is itself composed
of numerous separate populations. In the absence of detailed information
on personality in a large number of localities around the world, the best
way to look for evidence of personality varying with climate is through
examining racial variability.
Rushton and Ellis have assembled considerable racial information. (These
differences of course are related only to central tendencies, and any one
individual need not resemble his race with regard to any single trait.)
Theirs are the best summaries of non-morphological racial differences.
They deserve considerable credit for assembling this data. While they
interpreted their findings in differential K selection terms, their data
can also be used to test the male mating effort versus paternal
investment hypothesis.
Explaining Racial Variation by Mating Competition versus Provisioning
Let us start by taking the list of personality characteristics Rushton
assembled (1987, p. 1019; 1988, p. 1010; 1989a, p. 9; Rushton & Bogaert,
1989) and see whether a mating effort versus parental investment
framework can explain them. This can be done for most items.
Aggression
Negroids are reported (by Rushton) to be the most aggressive and
Mongoloids least aggressive (Caucasoids intermediate). From a
reproductive viewpoint, aggression's benefits include leadership
positions. These assist in obtaining multiple wives, and frequently
provide opportunities for extramarital relationships. Aggression also
produces children through rape. In warm climates, where extra wives can
be self-supporting, there are clear reproductive benefits to additional
wives. In cold climates, lower survival of children by the first wife
will provide a partial or even complete offset.
The disadvantage to high levels of aggression is that it leads to injury
or even death, either in the course of the conflict caused by the
aggression, or through retaliation by victims or society. In all climates
death eliminates, and disability reduces, the chances of fathering
additional children. However, in cold climates, death and disability are
more likely to lead to the death of existing children, while in warm
climates the mother is more likely to be able to rear her children alone.
This effect alone would make the optimal position on an
aggression-fearfulness continuum climate dependent.
Aggression also leads to interband raiding and warfare. These increase
sexual access to other bands' females. Direct access may be through rape
or wife capture. Indirectly, killing or defeating competing males reduces
mating competition. Wives are later obtained by courtship or exchange.
However, additional wives only contribute to reproductive success if
there is enough food to rear the resulting offspring. Where women supply
their own subsistence, warfare and wife capture can produce reproductive
gains. This is likely to be true in tropical areas. In cold areas, where
wives must be provisioned by hunting, additional children from captured
wives would divert scarce resources from other children, limiting the net
gain.
A defeat in interband conflict leads to deaths and injuries. In northern
climates, where the gains from success are small, and the losses large,
the relatively non-aggressive will leave more descendants. In tropical
climates, where the benefits are larger, selection will be for higher
aggression.
While Rushton interprets aggression as a r characteristic, this is
implausible. Gould (1982, p. 367) argues, "Since member of K-selected
species inhabit the same niche and compete for population-limiting
resources, it should not be surprising that these animals regularly fight
with each other for control of those resources. Among r-selected species,
on the other hand, fighting would be a waste of their most precious
commodity, time." In essence, if resources are abundant, organisms will
not benefit from fighting. Destroying other individuals is only
beneficial when it eliminates competitors, which is to say in K
conditions. In contrast, aggression appears unambiguously useful for
obtaining numerous matings, even if not for provisioning.
__________________
Dominance
Very similar comments can be made regarding dominance, where Negroids are
reported to be the strongest seekers of dominance and Mongoloids least
(Caucasoids intermediate). Dominance seeking leads to more mating
opportunities, but also to death and injury, which reduces the survival
of already born offspring, especially where male provisioning is
essential. If the extra wives that dominance and prestige provide cannot
be supported, the ability to attract them gives little reproductive
benefit.
Anxiety
Mongoloids are reported to be the most anxious, and Negroids least (with
Caucasoids in between). This is closely related to dominance seeking and
aggression, in that high anxiety deters dominance seeking and aggression.
The more prone an individual is to anxiety, the less likely he is to seek
additional matings beyond his first wife. It is usually not in the wife's
reproductive interest for him to either take additional wives, or to seek
extramarital relationships. She can be expected to have evolved to
threaten retaliation, and occasionally retaliate by leaving, attacking
the offending male, or enlisting the aid of her relatives or society
against him. Conducting an affair with another man's wife, or an
unmarried chaste female, or rape, all involve risk taking. Thus, where
the optimal male strategy is to devote less efforts to mating than to
provisioning existing children, high anxiety is selected for .
There are additional reasons for selection for high anxiety in cold
climates. One strategy for surviving the winter is food storage (see
Miller, 1991). Food storage is practiced only (with exceptions) in
societies whose growing seasons are less than about 200 days (Binford,
1980). Anxiety about food supply encourages storage, and discourages
their too rapid consumption. Where storage makes a difference, high
anxiety is selected for.
Coon's descriptions (1971, p. 26-39) of hunter-gatherer housing shows
that simple domed houses and lean-tos are used by southern people, while
igloos, plank houses, and pit houses are used further north. Pit houses,
roofed holes, are common among northern hunters because they protect well
against intense cold. Houses in snowy areas can collapse with a heavy
snowfall, and cause loss of life, as well as leaving the inhabitants
exposed to the cold. Collapse of a tropical conical hut, or lean to, is
only an inconvenience. Anxiety would appear to encourage the construction
of houses with adequate safety margins, and possibly an early start to
such construction. Thus, anxiety would appear to promote reproductive
success more in areas with snow than in tropical areas.
Anxiety about being caught in a freezing storm, or away from a warm
campfire overnight is likely to promote survival in cold climates. Thus,
stronger cold climates selection for anxiety is predicted. (Nelson [1969]
mentions the caution and absence of thrill seeking in Eskimos).
Impulsivity
Frequently, short term pleasures can be obtained by acting, but acting
requires risking adverse consequences. One who frequently takes advantage
of short term opportunities displays impulsivity. Those with high anxiety
levels are less likely to seek immediate pleasures. Thus, it is not
surprising that the ordering on impulsivity, Negroids highest, Mongoloids
lowest (Caucasoids in between), is opposite to the ordering on anxiety.
In particular, males frequently have the opportunity to father children
through extramarital relationships or rape. High impulsivity individuals
would be expected to more often act on these opportunities than would low
impulsivity individuals. Thus, impulsivity would be selected for where a
high mating effort contributed to fitness.
Delay of gratification
Closely related to impulsivity is the ability to delay gratification.
Mischel (1958, 1961c, 1971, p. 127) found a racial difference in
preference for delayed gratification. Trinidad Indians (i.e. India
origin) children would wait longer for a reward than Negro children,
although he interpreted this as reflecting the greater absence of fathers
among the Negro children. As is common in Negroid populations (see
below), many of the Negroes lacked a father in the home, while few
Indians lacked a father in the home. Cultural factors probably also play
a role, since Grenada Negroes were similar to Trinidad Indians (Mischel,
1961c). Delay of gratification was less in a Trinidad industrial school
for juvenile deliquents than in an ordinary Trinidad school, supporting
the theory that difficulty in deferring gratification (such as choosing
the immediate gratification obtainable from stealing, risking a future
punishment) contributes to criminal activity (Mischel, 1961a).
Gratification delay in Trinidad Negroes was found to be positively
related to Harris's Social Responsibility Scale, which conceptualized
responsibility "as a composite of attitude elements reflecting behavior
classifiable as reliable, accountable, loyal, or doing an effective job"
(Mischel, 1961a, b). Interestingly, the Trinidad Negroes scored much
lower than a similar aged (presumably predominantly white) US group,
which Mischel (1961a, p. 6) notes is "fully consistent with
anthropological observations."
It is not known how heritable the ability to defer gratification is,
although most personality variables appear to have a significant degree
of heritability. However, in one experiment, using Barbadian Negroes in
the Cambridge area, the mother's delay of gratification (choice of large
bottle of instant coffee in a week or a small bottle now) was found to be
correlated with the child's violating or not violating a prohibition in a
temptation situation (Mischel & Gilligan, 1964, p. 412). This suggests
both behaviors are reflecting a heritable trait.
Difficulty in delaying gratification and impulsivity makes provisioning
more difficult. Provisioning requires suppressing the desire to eat in
order to bring food back to the family. In warm climates, not eating food
when available would merely deny the male forager the nutrition required
to compete with other males, since his children will normally be fed in
any case.
Also, a food storage strategy for surviving the winter requires deferring
gratification. The impulse to immediately eat available food must be
resisted to store it, and later the impulse to eat the stores must be
resisted in order to retain them for later use. Survival through the
winter may require not only storing food, but also storing fuel, making
clothing, and building shelters. These activities require resisting
impulses to divert energy to activities with shorter term returns
(gathering non-storable food, drinking, or even flirting). Thus, there
are other reasons why seeking immediate gratification and impulsivity
would be selected against in cold climates.
Banfield (1974) has proposed that seeking immediate gratification among
the U. S. inner city poor (who tend to be Negroids) explains much of
their poverty. While he carefully denies believing in genetic differences
(like other writers of the time), it is plausible that this trait, like
most personality traits, has a genetic component. Furthermore, tropical
environments, such as that of Africa, are ones where hunter-gatherer
populations are described by Woodburn (1980) as "immediate gratification"
ones. He has described how for the Hadza of Tanzania, food is available
in the bush at any time, and that as a result there is little need to
plan ahead or to defer gratification. Thus, it is plausible that the
immediate gratification behaviors that Banfield blames for so many inner
city problems may be a continuation of tropical hunter-gatherer behavior.
Sociability
Sociability assists in learning of, and exploiting, mating opportunities.
However, time spent socializing reduces the time available for gathering
food and for other parental investments. Sociability often involves
remaining near the camp where others are located, while provisioning
requires leaving to forage. Thus, selection for provisioning will reduce
sociability.
It should be noted that if sociability leads to talking it would be
selected against in northern climates, where quiet is required for
hunting.
Extraversion
Extraversion represents a combination of impulsivity and sociability
(Eysenck & Eysenck, 1985). Thus, extraversion will be selected for where
selection for seeking copulations occurs, and be selected against in
other areas. Thus, it is not surprising that Negroids rank highest in
extraversion, and Mongoloids rank lowest, with Caucasoids in between.
Behavioral restraint
Rushton (1988, p. 1013) combined many of these characteristics and
described them in terms of behavioral restraint, with Mongoloids being
highest in behavior restraint, and Negroids being lowest (Caucasoids
intermediate). Behavioral restraint is not conducive to males seeking
mating opportunities, but is conducive to making high paternal
investment, which frequently requires resisting immediate gratification
opportunities.
Criminal activity
Criminal activity is closely related to behavior restraint, for which the
evidence is that Negroids are highest, Mongoloids lowest, and Caucasoids
in between (for documentation see Wilson & Herrnstein, 1985; Ellis, 1988,
p. 532; Jaynes & Williams, 1989, chap. 9; Rushton, 1990a). Paternal
investment theory would explain high crime rates as resulting from high
aggressivity and low empathy, altruism, and rule following behavior,
traits that contributed to tropical reproductive success. A contributing
factor is that the racial ordering for intelligence (Mongoloids first,
Caucasoids next, and Negroids last [Jensen, 1987 on Negroids; see
Rushton, in press, for other references]) is opposite to those for crime,
and criminal behavior is known to be more common among the less
intelligent. Intelligence differences have been offered as explaining the
racial differences in crime (Gordon, 1987).
If those selected for mating effort have higher levels of aggression,
lower behavioral restraint, and higher sex drives, it would be predicted
that rape rates would be higher. They are known to be higher in Negroids
than in Caucasoids (Brownmiller, 1975, pp. 213-216; Ellis, 1989, p. 94).
Child abuse is another form of crime. Abusing a child is the opposite of
investing in it. If cold climate fathers were selected for paternal
investment, their descendants should commit less child abuse. Caucasoids
do have lower child abuse rates than Negroids (Ellis, 1987, p. 159), and
Mongoloids the lowest (Ellis 1993, p. 171).
Sexual restraint
The form of behavioral restraint most sensitive to natural selection is
sexual restraint. With regard to a wide range of sex related variables,
including marital instability, Rushton (1988) and Rushton & Bogaert
(1987) show that Mongoloids are the most sexually restrained, and
Negroids least, with Caucasoids intermediate. Sexual restraint is the
ability to resist opportunities for copulation. Males that devote their
energies to paternal investment have less energy left for seeking
additional matings.
Two mechanisms could produce greater sexual restraint. The sex drives
(including those for seeking variety in partners) could be weaker, or the
inhibitions to sexual activity could be greater. That populations
exhibiting greater sexual restraint are also more restrained in other
ways suggests that part of the explanation is the greater inhibition
(discussed above).
However, populations may also differ in the strength of sex drives.
Selection for a stronger sex drive (and for a stronger desire for variety
in partners) appears a more efficient mechanism for increasing mating
effort than merely selection for less restraint. Generalized mechanisms,
such as changing anxiety levels, might prove counterproductive in
non-sexual spheres. For instance, less anxiety might encourage taking
excessive hunting risks.
Simpson and Gangestad (1991) show that the strength of the desire for
numerous sexual partners (what they call sociosexuality) varies
independently of the strength of the desire for frequent sex. It is very
plausible that both are genetically influenced. They (Gangestad &
Simpson, 1990; Simpson & Gangestad, 1991) present evidence that
sociosexuality varies with personality dimensions that have been shown to
possess heritable components. Gangestad and Simpson (1990) argue that
seeking separate partners, versus making a commitment to one partner
represent different reproductive strategies, but fail to consider the
possibility that the equilibrium percentage of individuals following the
different strategies may vary with the environment (and hence with race).
A genetic influence on the drive for sexual variety is also suggested by
the greater male desire for variety. This is probably caused by the
effects of testosterone (or another sex related hormone) on some part of
the brain. Genetically controlled variability in the number of receptors
or the level of hormones could produce variability in the strength of the
desire for sexual variety across populations.
Sexual behavior
Rushton and Bogaert (1987) document differences in sexual behavior.
Besides a literature review, they reanalyzed the Kinsey data on sexual
behavior in American whites and blacks. This showed greater sexual
activity in blacks than in whites. For instance, the black frequency for
coitus in their first marriage was 3.83 times per week for those aged
21-25 versus 3.11 for similar whites. The more frequent intercourse
within marriage suggests differences in sex drive, rather than in a
generalized restraint (which should not affect the frequency of marital
relations). Measures of the extent and frequency of extra-marital sexual
activity (p. 542) showed more activity outside of marriage among blacks
than among whites, with all reported measures being statistically
significant at the .001 level. Most black working class females believe
that a wife should expect running around (Staples & Johnson, 1993, pp.
156-157). ". . .Black females have their first full sexual intercourse
some years earlier than the typical White female." (Staples & Johnson,
1993, p. 77). Differences in either sex drive or in social restraint
could explain these differences.
Since age at first intercourse (Martin, Eaves, & Eysenck, 1977), and age
at first date, marriage, and first and second child appears to be
genetically influenced (Mealey & Segal, 1993), it appears appropriate to
consider hypotheses that population differences in sexual behavior are
also genetically influenced.
Differences in sexual restraint and in the number of sexual partners
predict racial differences in sexually transmitted diseases. Such
differences exist in the distribution of AIDS (Rushton and Bogaert,
1989). They had earlier been reported for syphilis, where the negro rate
(often approximated by the rate for non-whites) is a multiple of the
white rate, both in civilians and in the military (Aral & Holmes, 1984,
p. 130; Berg, 1984, p. 93; Lewis, 1942, p. 158). The reported gonorrhea
rate is 21 times as high in blacks as in whites, although part of this
difference may reflect better reporting from the public clinics
frequented by blacks (Aral & Holmes, 1990, p. 22). For the common herpes
simplex virus -2, the antibodies at ages 60-74 are found in over 80% of
black females versus slightly over 20% of the white females (Aral &
Holmes, 1990, p. 27). Pelvic inflammatory disease (caused by the spread
of gonorrhea and/or chlamydia to the upper reproductive structures of
women) is currently a major cause of female infertility in parts of
Africa.
The most plausible proximate explanation for racial differences in sex
drives is the possibility discussed below of differences in testosterone
levels at the relevant ages. Testosterone promotes male sexual activity
(Kemper, 1990, pp. 38-46).
Size of sex organs
One consequence of higher levels of puberty causing hormones could be
greater development of the sex organs. Rushton and Bogaert (1987) use the
Kinsey data to document longer penises and greater circumference of
penises in blacks than in whites. From other sources they find Mongoloids
to have shorter penises than Caucasoids. One condom manufacturer provides
for larger size condoms for Africa than for other areas, and the smallest
size for Asia (Wong, 1991). Mongoloids have smaller testes than
Caucasoids (Short, 1984; Diamond, 1986).
It would be desirable to have good quality measurements of Negroid testes
size, because the theory that they have been selected for high mating
effort would predict larger testes in order to win at sperm competition.
High levels of polygyny, and accompanying sperm competition, would select
for large testes and high sperm production, especially allowing for the
tendency for the largest number of wives to occur late in life. Among the
large apes, the species that have multimale mating systems (notably the
chimpanzee) have larger testes (Short, 1981; Smith, 1984).
The available evidence, while not of the highest quality, does not
confirm this prediction. Ajmani, Jain, & Saxena (1985) found the scrotum
diameters in 320 Nigerian males to be greater than had been reported for
Europeans, as predicted. An American study of adolescents (Daniel,
Feinstein, Howard-Peebles & Baxley, 1982) reported "There was no
significant differences in testicular volumes between black and white
adolescent boys. Any possible simple correlation with race was not
significant against the general variability of testicular volume." No
actual report is provided of the racial averages, leaving the possibility
that some difference was found. In any case, a difference in adolescents
might reflect only an earlier start to maturation among the blacks. In
addition, one early autopsy study actually found lower testes weights in
Negroids than in Caucasoids (Freeman, 1934).
Rushton and his colleagues explain these sex organ differences with his
differential K selection hypothesis. Yet it is not obvious that larger
penises (or clitorises or vaginas) lead to more offspring. Thus, they
should not be interpreted as r characteristics. More plausibly, they are
a mere by product of selection for high levels of sex hormones. The
testosterone surge at puberty enlarges the penis, and it is plausible
that higher hormonal levels would produce a larger organ. Testosterone
increases the penis size of castrated rats whether applied externally or
injected (Wigodsky & Greene, 1940). This makes it more plausible that
racial differences in penis size reflect hormonal differences.
Body build
There are racial differences in body build. Negroes have a more masculine
body build than Caucasians (Laska-Mierzejewska, 1982). The masculine body
build implies strong accentuation of such masculine characteristics as a
large chest, and muscular body. Negro soldiers (males) have been found in
two studies to be more mesomorphic (and less endomorphic) than white
soldiers, with the difference being more than one standard deviation
(Damon, Bleibtreu, Elliot, & Giles, 1962, Table 2).*(3). Simply put,
mesomorphy is the amount of visible muscularity. Such a body appears to
have been selected for conflict with other males. Notice, this
observation is evidence for paternal investment theory, since other
theories do not predict that the Negroid males will be more masculine.
However, the Japanese are relatively mesomorphic, both in Hawaii (Heath,
Hopkins, & Miller, 1961), and in Japan (Kraus, 1951). Thus, the extent of
mesomorphy appears to be one case where Ruston's generalization that the
Caucasoids fall between the Negroids and Mongoloids breaks down.
Hudson & Holbrook (1982) found lower mean fundamental vocal frequencies
in Negro males and females than others had found for whites. As is well
known (and found by them), males display a lower frequency (deeper voice)
than do females, and puberty deepens the male voice. This deepening is
generally attributed to testosterone. The deeper Negro voice may reflect
the influence of higher testosterone levels at puberty or prenatally.
Muscle characteristics
An interesting set of statistically significant differences in muscle
characteristics has been found between black and white sedentary males
(Ama, Simonau, Boulay, Serresse, Theriault, and Bouchard, 1986). African
blacks were found to have less type I muscle fibers, more type IIa and
lower activities in enzymes catalyzing reactions in phosphagenic and
lactase dehydrogenase metabolic pathways. These were interpreted as
likely to be inherited, and suggesting that blacks would exhibit better
performance in sports requiring a short duration of exertion. Malina
(1988) reviewed the literature on childhood performance, and found that
blacks excelled in the dash, the standing long jump, the vertical jump,
and the ball throw for distance. All of these involve a short burst of
exertion. Tests with a bicycle ergocycle have shown Caucasians to have
higher maximal O2 uptake, a trait adapted for endurance activities. Also,
Ama, Lagasse, Bouchard, and Simonau (1990) reported better white
performance (compared to black West Africans) in the last 30 seconds of a
90 second knee extension exercise, a result consistent with blacks making
greater use of anaerobic energy metabolism than whites. What would have
selected for racial differences in such traits?
Hunting is implausible both because Caucasoids are likely to have hunted
more than Negroids, and because hunting often requires prolonged exertion
to follow large animals. A likely explanation is male fighting, since
fights often involve short periods of vigorous exertion (after which the
opponent is hopefully defeated). Thus, Negroids appear to be selected
more for fighting. This would be consistent with their more muscular body
build and higher aggression. It is what would be expected if Negroids had
been selected to win mating competitions.
Blacks have denser and stronger bones than whites (Himes, 1988; Pollitzer
and Anderson, 1989). The disadvantage to higher density bones is higher
weight (more energy required for movement) and greater need for calcium.
The advantage is fewer fractures, and thus, lower mortality. The bone
differences can be explained if black males engaged in more intermale
conflicts, and those with stronger bones were less often injured. No
other hypothesis comes immediately to mind that can explain these density
differences.
Worthy (1977, chapter 2; Worthy & Markle, 1970; see also Jones & Hochner,
1973) has shown systematic differences in the sport positions blacks and
whites play. He argues that where the positions require reacting properly
to the opponents' actions, blacks are more successful, while whites do
better where the player initiates his own motions, as in baseball
pitching, marksmanship, or in shooting a basketball free goal. He reports
a Negroid relative advantage in the defensive position of an experimental
game where they had to react to their opponents' initiatives.
Worthy also correlated eye color with positions played. Dark eyed whites
are overrepresented in the same positions in which blacks are
overrepresented. In Worthy's theory, eye color plays a direct role.
However, eye color also varies with ethnic origin, with north Europeans
having more blue eyes. This suggests an Old World cline such that ability
to react to opponents' actions increases to the south.
What circumstances would have selected for these different abilities?
Survival in fights with other males would appear to depend on quick
reactions to opponents' moves. In contrast, a hunter usually stalks his
prey and then chooses the time to attack. Worthy's observations could be
explained if male reproductive success in colder regions varied with
hunting ability, while in the tropics it varied more with fighting
ability. The eye color differences could be explained if hunting was even
more important in northern Europe than in southern Europe, or if southern
Europeans had interbred more with farmers of Middle Eastern origin.
Possibly relevant evidence is provided by Coleman (1980). Successful
prone rifle shooters (who choose the moment of shooting) are the most
introverted, while successful rapid fire pistol shooters (who have very
little time to fire five shots, and have to move the pistol from target
to target), are very extroverted. Apparently personality correlates with
what looks like Worthy's reactive versus non-reactive distinction. Thus,
an alternative explanation for these racial differences would rely on
selection for different personality traits. Since tropical climates seem
to select for both quick reactions (as in fighting) and for extraversion,
and cold climates for the opposite, both theories predict a similar
north-south behavioral gradient.
There are other intriguing reports of correlations of eye color with
behavior. Rosenberg & Kagan, (1987, 1988) and Rubin & Both (1989) report
that Caucasian children that are behaviorally inhibited ( a concept
related to introversion) are disproportionately blue eyed. While
Rosenberg & Kagan suggest several possible biological mechanisms for this
effect, a very plausible explanation is that north European children
(more likely to be blue eyed) are more behaviorally inhibited than South
European children (who are more likely to have brown eyes). Both eye
color and behavioral inhibition are believed to be genetically
influenced. If the effect is really biological with both eye color and
behavior having a common cause (a pleiotropic gene effect), it would be
predicted that where one sibling was blue eyed and one brown eyed, that
the blue eyed one was more likely to be behaviorally inhibited. If the
genes for eye color and behavior were associated merely because the
ancestors of different children came from different regions, there would
be no sibling correlation. Unfortunately, such a study has not yet been
done.
An argument against Negroids having evolved for fighting is that they
show lower pain tolerance than other races (Worthy, 1977, pp. 123-124)
Life Span Variations
Negroids have shorter lives than Caucasoids, who have shorter lives than
Mongoloids. For instance, U. S. whites have a life span estimated at 76.1
years versus 69.1 years for U. S. blacks (U. S. Department of Health and
Human Services, 1993). If testosterone shortens life (Hamilton, 1948), as
it appears to do (shown by the shorter life span of males than females,
and of normal males compared to castrated males), differential
testosterone levels could explain the life span ranking.
Part of the shorter Negroid life span reflects more violent and
accidental deaths, which could result directly from higher aggression.
However, disease causes most of the excess deaths. As a general rule,
more polygamous species have higher male death rates (relative to female
rates), with much of the difference being due to degenerative diseases
(Daly and Wilson, 1988, p. 142). As discussed below, Negroids appear to
be more polygamous than other races.
An evolutionary biology theory of aging (Rose, 1991) holds that many
genes are pleiotropic (i.e. have more than one effect). The same genes
that contribute to longer life often impose disadvantages earlier in
life. In the simplest case, genes which delay degeneration (perhaps
through directing more energy to cell repair) also imply early life
disadvantages (perhaps through leaving less energy available for mating
or for lactation). A longer life can be purchased only at the expense of
an earlier reproductive disadvantage. Which genes are selected for
depends on whether reproductive success is facilitated more by a long
life, or by early life success. This may depend on whether selection is
for high paternal investment or high mating effort.
Copulation precedes childbirth, while paternal investment follows
childbirth. Since death destroys a man's ability to help his children,
longevity facilitates paternal investing. Thus, if a father's death hurts
his child's survival chances, selection for a long life will be stronger
than if children can be raised without paternal assistance. Conversely,
if an early death from mating competition is going to eliminate any
reproductive benefits from slower degeneration later, the alleles that
protect against degeneration in old age will be less beneficial (Diamond,
1992, Chapter 7, especially p. 132).
If a male does not obtain a mate when young, living longer will not add
to his descendants. Suppose the number of matings determines how many
descendants a man leaves. Then men are more likely to be selected for
early vigor and competitive ability, even at the expense of an earlier
death. Where males have been selected for mating competition, polygyny
often emerges (see below). For many men to have multiple wives, others
must have no wives. Thus, to perpetuate his genes in a polygynous
society, a man must be ranked relatively highly by those who control
sexual access. Dominance and prestige seeking would be selected for.
In a monogamous or nearly monogamous society, even undesirable men marry.
Suppose genes that handicap men in mating also contribute to a longer
life, and hence to greater offspring survival. Then carriers of these may
leave more descendants than worse providers who are better at mating, but
who still get only one wife. Genes for high testosterone probably shorten
life but may contribute to mating success through stronger muscles,
higher sex drive, and aggression. Many athletes shorten their lives by
taking steroids (essentially synthetic testosterones) to promote
competitive success.
Thus, strong male sexual competition leads to a shorter life span. This
can be explained by paternal investment theory. In differential K theory,
earlier deaths (in advanced countries, Negroids die earlier than
Caucasoids, and Caucasoids earlier than Mongoloids) are interpreted as a
result of going through the life cycle quicker. A long life span is thus
a K characteris
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