A couple of weeks ago, I sat for a pretty long interview (about an hour) at the offices of Big Think in New York. They'll be releasing edited bits over the next few weeks. Here's the first one.
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just read some posts here that talked about female orgasm vocalizations...and then happened to start reading about female tennis and the females with their loud vocalizations and couldn't help but relate the two.
forgot to mention how i enjoy reading your posts and to keep up the good work! i plan to get sex at dawn this week.
thanks for giving me a little bit of education and insight in my day
We are equally related to chimpanzees and bonobos because they share a common ancestor about one million years ago.
After the Pan/Homo lineage split some six million years ago the Pan lineage evolved their own mating systems and there were selective sweeps on genes connected to reproduction such as the SEMG1 gene for the rubbery copulatory plug. They also evolved their sexual swellings after the split.
Our lineage quickly became bipedal and the fossil evidence supports greater sexual size dimorphism. We evovled our multimale/multifemale system sometime later - perhaps a lot later.
Along the way we have all kinds of hominin ancestors and cousins - also equally related to chimpanzees and bonobos - who show all kinds of variation, which likely means all kinds of social and breeding systems as they encountered all kinds of different ecologies.
Meanwhile, back in the forest, chimpanzees were spread across central Africa. About one million years ago a small founder population became separated from the rest of the chimpanzees and evolved into the bonobos with the particular founder gene pool in a particular environment evolving into what we know as the bonobos.
The modern bonobo is confined to a single area, Cuvette Centrale, in the centre of the Congo Basin in the Democratic Republic of the Congo. The Congo River is to the north and the Sankuru and Kasai rivers are in the south. North of the River Congo are the 3-4 subspecies of chimpanzees across central Africa, along with the various subspecies of gorillas.
To say that we have chimpanzees on one side and bonobos on the other side, with us in the middle, is incorrect.
If the last common ancestor of chimpanzees and bonobos was more bonobo-like then we would have to argue that it was the massive numbers of chimpanzees that had to evolve away from that while the bonobo founder population kept more true to their shared ancestral origins. Extremely unlikely.
For the selective sweep in Pan see:
Kingan, S. B., Tatar, M., and Rand, D. M. (2003). Reduced polymorphism in the chimpanzee semen coagulating protein, Semenogein I. Journal of Molecular Evolution, 57: 159-169.
For bonobos from a founder population see:
Schaller, F., et al. (2010).Y Chromosomal Variation Tracks the Evolution of Mating Systems in Chimpanzee and Bonobo. PLoS ONE, 5(9): e12482.
Note that they say;
"Although, loss of variation of the Y chromosome in the bonobo by a founder effect or genetic drift cannot be excluded, these contrasting patterns might be explained in the context of the species' markedly different social and mating behaviour. In chimpanzees, multiple males copulate with a receptive female during a short period of visible anogenital swelling, and this may place significant selection on fertility genes. In bonobos, however, female mate choice may make sperm competition redundant (leading to monomorphism of fertility genes), since ovulation in this species is concealed by the prolonged anogenital swelling, and because female bonobos can occupy high-ranking positions in the group and are thus able to determine mate choice more freely."
Bonobos Fall within the Genomic Variation of Chimpanzees
"To gain insight into the patterns of genetic variation and evolutionary relationships within and between bonobos and chimpanzees, we sequenced 150,000 base pairs of nuclear DNA divided among 15 autosomal regions as well as the complete mitochondrial genomes from 20 bonobos and 58 chimpanzees. Except for western chimpanzees, we found poor genetic separation of chimpanzees based on sample locality. In contrast, bonobos consistently cluster together but fall as a group within the variation of chimpanzees for many of the regions. Thus, while chimpanzees retain genomic variation that predates bonobo-chimpanzee speciation, extensive lineage sorting has occurred within bonobos such that much of their genome traces its ancestry back to a single common ancestor that postdates their origin as a group separate from chimpanzees.
Why don't chimpanzee and bonobo males have sex with females who don't show (sometimes false) signals of fertility? Does the dick not work right without being fooled into thinking there's an egg there or something?
What happens, or would happen to female chimpanzees and bonobos that said 'no'? In chimpanzees they are sometimes raped/coerced/'trained' to submit.
In bonobos at Lomako White has seen violence of males, and sexual coercion.
A lot less in bonobos, no doubt, so presumably if the females did choose to say no there would in fact be more male violence and sexual coercion?
Female bonobos often exchange sex for food. If they didn't would they get to eat enough?
It looks like female chimpanzees and bonobos do not really get much real choice in the matter - Hobson's choice, perhaps? Though higher status female bonobos can say no more often - they can have the back-up of other females.
And this sex then is also reproductive sex in that it improves the female's reproductive success by her avoiding injury from males or getting food.
For humans, this could translate into removing rape and sexual coercion by the females simply not saying no? After all, they must 'naturally' be hypersexual too and wanting sex for sperm competition or, when not ovulating, just for the pleasure of it like the males, so why say no? Their bodies want it even if their mind's might not know it.
As men have often said 'No' actually means 'Yes' - the girls are just too scared, or ignorant of their own wants to be open and honest about it.
Christopher Ryan, Ph.D., is co-author of Sex at Dawn: The Prehistoric Origins of Modern Sexuality (HarperCollins 2010).