Since our closest living relative is the chimp and the dwarf chimp (bonobo), we should logically share characteristics with them and also be able to trace our divergence from their species. Among the shared features between humans and chimps are the following: the same number of fingers and toes with opposable thumbs, no tails, somewhat flattened, forward-looking faces with close-set eyes, stereoscopic color vision, 32 teeth, the ability to make and use tools, prolonged period of parenting, similar sense organs of sight, smell, hearing, and touch, similar body language (chimps play, hug, kiss, tickle, pat each other on the back, pound and shake their fists), and according to Dr. Jane Goodall, chimps also display joy, sorrow, fear, surprise, anger, and empathy. They can also be trained to recognize themselves in mirrors, which most animals can’t do.
Of course, there are obvious differences between our two species: we are relatively hairless, walk on two feet with erect postures, have shrunken canine teeth, and possess greatly enlarged brains. Our hairy cousins walk on all fours, have a standing height between 3.5 and 5.5 feet and generally weigh between 60 to 130 lbs. They are both terrestrial and arboreal and sleep in trees to avoid predators. Their arms are longer and can extend below their knees. Chimps are also four times stronger and much faster than humans at short distances (25 mph compared to 15 mph for humans).
It is important to understand, however, that we didn’t evolve from chimps. We have a shared ancestor, and our species diverged from chimps and apes about 7 million years ago.
There are countless fossil specimens that illustrate the evolution of original ancestors to transitional forms to the current species. Within these spectra we see species adapting to new environments, changing conditions, etc. by modifying or radically altering body parts to meet the new conditions of exploration or survival. For example, a stunted forelimb evolves into a feathered wing or tails retract until they only remain as embryonic vestiges.
The evolution of the whale began about 52 million years ago with the Pakicetus, a land animal the size of a wolf who walked on all fours, ate meat but also loved fish. Ambulocetus evolved about 2 million years afterward; it could walk on land as well as swim in the water. A few million years later Rodhocetus evolved with an elongated skull and body, nostrils moved backward and hindlimbs that were retracting and almost worthless on land. It appeared this mammal was heading to the sea. Dorudon appeared about 40 million years ago in the fossil records and appeared to be completely aquatic with tiny hind legs, a tail, forelimbs that became flippers, an even more elongated body with a shortened neck, and a blowhole on top of its head.
According to current fossil records, whales evolved over the course of about 12 million years. Humans evolved much faster over about 7 million years. Nevertheless, this isn’t the Garden of Eden where Adam and Eve were created on the sixth day of God’s labors in their current form on a planet that is only 6,000 years old. (to be continued in next post)