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| foundamental text S@D http://sexatdawn.com/CITAZIONE G.F.Miller: "evolutionary innovations seems focused on the details of penis shape
body-size dimorphism: the average difference in size between adult males and females in a given species. among apes for example, male gorillas and orangutans average about twice the size of females, while male chimps, bonobos and humans are from 10 to 20 percent bigger and heavier than the females. male and female gibbons are of equal stature. among mammals generally and particularly among primates, body-size dimorphism is correlated with male competion over mating (Lawler 2000).
the biggest, baddest gorillas will pass genes for for bigness, badness into the next generation.
on the other hand, in species with little struggle over females, there is less biologicale imperatvie for the males to evolve larger, stronger body, so they normally don't. that's why the sexually monogamous gibbons are virtually identical in size.
looking at our modest body-size dimorphism, it's a good bet that males haven't been fighting much over females in the past few million years.
without access to the skeletal data on body-size dimorphism we have today, Darwin speculated that early humans may have lived in a harem-based system.
the culturale conditions necessary for some males to accumulate sufficient political power and wealth to support multiple wives and their children simply did not exist before agriculture. if the origin of our nuclear family/sexually is monogamous mating system, why aren't men and women the same size, like gibbons? if humans are naturally polygynous, why aren't men twice the size of women like gorillas? CITAZIONE note the assumption shared by both these interpretations: female sexual retiscence. in both scenarios , female "honor" is intact. in the second interpretation, only the male's natural fidelity is in doubt. CITAZIONE Winge coined the word sperm competition; G.Parker later defined the concept. if the sperm of more than one male are present in the reproductive tract of an ovulating female, the spermatozoa them-selves compete to fertilize the ovum. females of species that engage in sperm competition typically have various tricks to advertize thei fertility, thereby inviting more competitors. their provocations range from sexy vocalizations or scents to genital swelling that turn every shade of lipstick red from Berry Sexy to Rouge Soleil. CITAZIONE NOTE: as we'll discuss in the next chapter, the genital echo theory posits that women developed pendulous breasts so that the cleavage would mimic the (is there a scientific term for this?) butt-crack that so enticed our primate ancestors. following that line of reasoning, some argue that fancily named lipstick serves to re-create the bright red "hinder ends" that so perplexed poor Darwin. male apes living in multiple social groups (such as chimps, bonobos and humans) have larger testes, housed in an external scrotum, mature later than females, and prduce large volumes of ejaculate containing greater concentrations of sperm cells than primates in which females normally mate with only one male per cycle (such as gorillas, gibbons and orangutans). even if Darwin suspected something like sperm competition had palyed a role in human evolution, he could hardly be expectes to drag the angelic Victorian woman down from her pedestal. |
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