The group of apes are some of our closest neighbours. So, let's dicuss about them in this short piece.
Chimpanzees and Bonobos
Chimpanzee and bonobo joined forces about two million years ago and their common ancestors joined with that of ours(Human) about 6 million years ago. That means as we approach out common ancestor (concestor) chimps are also coming from another direction. They meet with us in the Pliocene forest. It seems more evolutionary changes has occurred along the human line of descents from common ancestor. Our shared ancestor might be hairy, with chimp size brain, omnivorous, might be capable of precise nut cracking ability. They might made and use tools with occasional bipedality as well. Obviously geographical barriers might have separated us from them.
It has been scientifically proven that chimpanzees and bonobos are more closely related than they are to gorillas. We- the humans, are even equally close with chimps and bonobos. Bonobos use sex as currency of social interaction like somewhat we use money. They use copulation to assert dominance, to cement bonds to other troops including small infants.
Gorillas
Only one million years further down from there, we meet our another common ancestor with gorillas. That means 7 million years ago our lineage separated from that of Gorillas, which further means that up to that time, we two were brothers. Africa was more forested even Sahara would have been wooded Savannah. Concestor might be more ape like. That means Gorillas could have gone major body transformation later during evolution like we did after the separation with apes. Heavy black pigmentation in the body might explain the protection against UV rays that falls directly in tropical forests. Gorillas are entirely vegetarian with males having harem of females.
Orangutans
Now going back in time about 14 million years, in the Miocene epoch, Africa witnessed a great flowering of ape life in early Miocene, in the form of Proconsulids. Many authorities agree that Ramapithecus (or Shivapithecus) is close to the line that gave rise to orangutan.
Evidence been found to support the idea that there has been multiple migrations between africa and asia. And it is believed that concestor 3 might have lived in Asia. Its been speculated that, our ancestral lineage hopped sideways out of Africa around 20 Million years ago flourished in Asia until around 10 Mys ago and then hopped back to africa. There were land bridges available across Arabia at right time for passage and remember we are talking on the scale of millions of years and world is a big place, we can't reject the idea of major migration in such a big world in which major land masses are connected.
Surviving apes descended from lineage that migrated out of Africa to Asia. Gibbons and Orangutans descendant of that migrants who stayed in Asia. Later descendants of migrant returned to Africa where earlier miocene apes had gone extinct. Those migrants gave Gorillas, Chimps, Bonobos and Us.
Gibbons
Going back 18 MYs, Probably in Asia, we might encounter small apes as our concestor and at which point Gibbons will also join forces with our lineage. Those ancestors use bipedal walking to travel along long branches and use brachiation to travel across branch to branch. They might have weak brachiating arms, gibbon like face and no tail with short snout.
Old world monkeys
About 25 million years ago, Africa was isolated from rest of the world, our ape line of lineage first time joins with the tail bearing pilgrim in the modern day i.e Old world monkeys. All the old world monkeys scattered in the world join hands about 14 MYs ago in their own way. Down facing of nostril, female showing full menstruation, ear tube with tympanic bone unlike new world monkeys whose ear lacks bony tube. These things pretty clearly place them our closer relative and some sort of long distance brother in a way. Concestor 5 was tailed while concestor 4 was tailless.
New world Monkeys
Going about 40 million years back we meet yet another ancestor whose another branch is now commonly called as New world monkeys. They might have come from Africa through chains of exposed island by hopping and monkeys might have rafted across. It might seems odd to suppose, pregnant female monkey in floating mangroove to reach different land mass. But given tens of Millions of years it becomes almost inevitable and occuring only once is enough for it. Prehensile tailed new world monkey is most common in south america. New genes duplicate of the original genes go separate ways by mutation, selection and drift.
During those early days nocturnal mammals had no color vision. But coming to primates why good color vision be important ? The answer might be for body adaptation as eating of fruit and seed dispersal became their natural habit. We have trichromatic retina for three types of cone cells for blue, green and red. And their visual range covers violet, yellow, orange colors as well, all seemed useful for the type of adaptation in the jungle monkeys.
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