Bonobos as models for human ancestors
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21-05-2012, 08:08 PM
RE: Bonobos as models for human ancestors
The documentary above (I forget which part) explains how an archaeologist taught Kanzi how to make a flint knife using stone knapping techniques. Kanzi developed his own technique of simply bashing two rocks together to make the knife. The flint is indeed sharp enough to cut a rope. Here is a short video of Kanzi making such a knife. This is probably similar to how our early ancestors came across such techniques. What's funny is that he uses his lips to test the sharpness. Chimpanzees are known to test various things with their lips in a similar fashion:



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22-05-2012, 09:24 PM (This post was last modified: 23-05-2012 12:42 AM by ghostexorcist.)
RE: Bonobos as models for human ancestors
I wanted to share some interesting information regarding human evolution. The book Before the Dawn (2006) by Nicholas Wade states that there are two types of modern humans: anatomical and behavioral. The former were fully formed humans, with heavily built skeletons, who appeared around 150,000-200,000 years ago. The latter were lightly built humans, with all of the behaviors common to us, who appeared 50,000 years ago. Wade mentions that there was something that had to have changed humans’ way of life in order to cause their skeletons to reduce to modern proportions. He recalls that body dimorphism between male and female Chimps and Gorillas are striking. For instance, male Gorillas are twice the size of the females. However, there is a smaller body size difference between Bonobos. Wade thinks more equalization in body size led to a more egalitarian society. Egalitarian societies require individuals to be less war-like. But how would this equate to a smaller bone structure? This is when he mentions the famous silver fox experiment. Over the course of 50 years, Russian scientists selected tamer silver foxes and mated them. The following generations became tamer and tamer until the 8th generation, when the offspring began to exhibit the dog-like characteristics of lower tails, droopy ears, and fur patterns not known to the species. Wolf cubs tend to have dog-like characteristics until they reach a certain age, so scientists believe that the selective breeding of tamer wolves led to the resulting dogs to retain juvenile characteristics, including lighter skeletons. Therefore, it’s possible that some form of (female) sexual selection of tamer human individuals caused the same shift in skeleton size.

Chimps live in areas with less fruit-bearing trees and protein rich plants than the Bonobos. Males in wild Chimp communities bond by hunting monkeys and sharing meat. Females are forced to hunt for food on their own, which means they never form bonds. Males fight to be in the alpha spot, which means females choose larger males to mate with to have stronger offspring. This explains the patriarchal society and the difference in dimorphism. Since Bonobos have more food resources, females are able to come together to form bonds. This means they are able to band together against males. Females probably chose to mate with smaller males. This explains the matriarchal society and the more equalization in dimorphism. This probably happened to equalize the size between the human genders. The alpha male in Chimp communities usually directs hunts and gets the biggest share of meat. But because there is less food competition in Bonobos, there is more sharing and no showboating. This recalls egalitarian societies like the !Kung people of southern Africa (! = click noise (awesome, right?)). All men hunt together, but there is no prestige for the man who makes the biggest kill, nor does he get a larger share. All of the people of the tribe share in the meal. Therefore, larger food resources in our early lineage probably led to egalitarian-type hunter-gatherer societies.

The book Bonobo: The Forgotten Ape (1997) by Frans de Waal mentions that some scientists consider Bonobos to be what our original ape-like ancestors looked like. However, Bonobos are known to have split off from Chimpanzees about 3 million years after the human lineage split with Chimps from the common ancestor. Bonobos are less aggressive and have much lighter skeletons (again, a juvenile characteristic) than Chimps, and, as mentioned above, the difference in dimorphism between males and females is not as drastic. Other scientists have suggested that the original human ancestor had traits common to both Chimps and Bonobos. I agree, but based on the Russian silver fox experiment, it’s very possible that the reduction in skeleton size due to sexual selection could have happened more than once. This would mean that the original ancestor would have been bigger like a Chimp.
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26-05-2012, 09:30 PM
RE: Bonobos as models for human ancestors
Interesting! I am quite convinced that Evolution is a fact ( if that is acceptable.). This has made me honestly interested even more in learning what I can about our history as living things. Thank you.

[Image: 0013382F-E507-48AE-906B-53008666631C-757...cc3639.jpg]
Credit goes to UndercoverAtheist.
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04-06-2012, 03:59 PM
RE: Bonobos as models for human ancestors
As I've mentioned in a previous post, the vaginas of Chimps and Bonobos swell to the size of giant bubble gum pink beach balls. This lets the males know when they are in full estrus. Here is a rather gross example:

[Image: bonobo_full_estrus.JPG]

Now, Chimps have a shorter period of receptivity, which leads to fighting between males for mating rights. Obviously, the alpha male is going to get the prime nooky first, and then he will allow the males who have aligned with him to have their time with the ladies. The remaining fertile males are not so lucky; they either have to fight their way to the top, or mate in secret in order to avoid a possible fatal beating. Since most babies born in a wild community belong to the alpha male, any male who fights his way to the top and usurps the throne will kill the newly born offspring to make way for his own genetic progeny.

Bonobos, on the other hand, have a much longer period of receptivity (i.e., their genital swelling stays longer than the time in which they can become pregnant). This means that there is less competition between males since each can have multiple turns of mating with numerous females. This in turn means that there is no need for infanticide since none of the males can figure out the parentage of each new generation. All of this combined leads to an overall more peaceful society.

Frans de Waal suggests that the original ancestor of humans and Chimps did not have the genital swelling and that it developed after the split. This would explain why Chimps and Bonobos have it, but we don’t. But then again, other species of primates like Orangutans, Gibbons, and Baboons have the swelling. Orangutans and monkeys are further down the human family tree, so the swelling seems like an older adaptation. Perhaps our lineage lost the swelling as we moved more towards pair bonding. Covert fertilization would lead to less fighting just like the extended period of estrus in Bonobos.
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15-06-2012, 11:45 AM
RE: Bonobos as models for human ancestors
The Bonobo genome was recently published. Here are some interesting results:

Quote:http://primatology.net/2012/06/14/the-co...bo-genome/

* Bonobos and chimps have 99.6% sequence similarity
* Bonobos and humans have 98.7% sequence similarity
* The split of bonobo and chimpanzee is confirmed to have approx. 1 million years ago, with no inbreeding occurring
* 6% of the bonobo genome has evidence of incomplete lineage sorting(when an allele does not match the population history of a species). This has lead to the observation that ~1.6% of the bonobo genome is more similar to humans than chimpanzees
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19-06-2012, 11:21 AM
RE: Bonobos as models for human ancestors
I mentioned earlier that evidence suggests sexual selection for tamer individuals--just like the Russian experiment involving the Silver Foxes--caused the Bonobos and possibly the ancestor of Humans and Chimps to take on juvenile characteristics. Now scientists are starting to find out that other animals experienced this shift. I think this probably explains many of the lifeforms that inhabit the earth today. Neat stuff!

ScienceDaily (May 30, 2012) "Evolution of Birds Is Result of a Drastic Change in How Dinosaurs Developed"

Quote:Researchers from Harvard University, The University of Texas at Austin and elsewhere have found evidence that the evolution of birds is the result of a drastic change in how dinosaurs developed. Scientists have long understood that modern birds descended from dinosaurs. Rather than take years to reach sexual maturity, as many dinosaurs did, birds sped up the clock -- some species take as little as 12 weeks to mature -- allowing them to retain the physical characteristics of baby dinosaurs.

The results of the study appeared May 27 in an online edition of the journal Nature.

"What is interesting about this research is the way it illustrates evolution as a developmental phenomenon," said Arkhat Abzhanov, associate professor at Harvard and study co-author. "By changing the developmental biology in early species, nature has produced the modern bird -- an entirely new creature -- and one that, with approximately 10,000 species, is today the most successful group of land vertebrates on the planet."

While it's clear simply from looking at the skulls of dinosaurs and modern birds that the two creatures are vastly different -- dinosaurs have distinctively long snouts and mouths bristling with teeth, while birds have proportionally larger eyes and brains -- it was the realization that skulls of modern birds and juvenile dinosaurs show a surprising degree of similarity that sparked the study. . . .

[Image: 120530212105-large.jpg]

Skulls of three types of archosaur—alligator, primitive dinosaur, and early bird. The left column represents juveniles and the right column represents adults. (Credit: Image courtesy of The University of Texas at Austin)

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