We must always be prepared for a paradigm shift in our thinking on subjects like human evolution. Nothing is etched in stone. We are still in the process of reconstructing the progress of the evolution of this world from its early beginnings and of the life upon it and if we allow ourselves to appreciate the whole picture then we must agree that by far the puzzle is far from complete. There is indeed much work yet to be done.
The established school of thought on the evolution of humans is pretty much ingrained into the conscious of most students - that is, humans evolved from apes, or ape-like creatures, who began their evolution into intelligent beings by climbing around in trees. Scientists making observations of orangutans standing upright on branches in the forests of Borneo so as to be better able to reach ripe fruit have linked their human-like behavior to evolutionary theory. An article in the Toronto Star stayed on the topic: "Scientists who spent a year photographing orangutans in the rain forest say the trait probably evolved in ancient apes navigating the treetops long before ancestors of humans climbed to the ground...". Any deviation from the idea that we learned to walk only long after we were well practiced in the art of climbing trees teeters dangerously on the brink of crank science. The following excerpt from a page buried in the News in Science web site daren't suggest otherwise: "Humans were born to run and evolved from ape-like creatures into the way they look today probably because of the need to cover long distances and compete for food, U.S. scientists say."
I am not averse to taking risks. After all, I have no scientific reputation to uphold. If my car had a bumper sticker it would read "I'd rather be a crank - I can say anything I want."
I actually doubt strongly that humans actually evolved from ape-like creatures, and while I won't declare outright that at some point in evolutionary development a regression of sorts might even have taken place which saw some species of human-like creatures taking to the trees because they couldn't run fast enough to escape their predators I won't dismiss that theory altogether either.
We must accept that evolution is very much a function of environmental adaptation and that the Earth's environment is very diverse across the globe. We should also note that humans represent the peak of evolutionary development and as such have probably been evolving for the longest time of any creature that hasn't yet become extinct. I think it a flawed exercise to compare a chicken leg to a dinosaur's leg. Too many millions of years separate the two. I believe that lizards and reptiles alive today are more closely related to early dinosaurs than birds are because of their obvious similarities. I also think it improbable that any ape, whether Orangutan or Bonobo chimp, who also routinely walk upright for short distances, will ever develop the skill to maintain that posture let alone become fast bipedal runners. I think that they are a different creature altogether. It is above all most apparent that creatures tend to settle into the niche that circumstance has led them to fall into and that apes for example have been and are continuing to evolve into better apes.
I strongly believe that humans are direct descendants of an omnivorous dinosaur whose staple diet was the eggs of other dinosaurs and that they evolved their longer arms to more easily clutch their booty to their chests to be better able to run away from angry mother dinosaurs on the two strong legs that evolved specifically for that purpose. Not many creatures eat eggs as a staple food of their diet. It is precisely this fact that has enabled the growth of our brains to its much larger size, since a very large part of the brain is cholesterol. About 25% of the total amount of the cholesterol present in humans is found in the brain. Our current physical form owes its appearance to the steady state of affairs which allowed this slow process to occur over the immense time frame that is required for the development of a larger brain. Eggs are extremely rich in essential nutrients, and when combined with fruits, nuts and roots, makes for a very healthy animal. This varied diet only contributes all the more to the potential for the development of intelligence. Insomuch as teamwork for food procurement lies at the root of the development of society the clever planning of strategy to distract a fierce mother dinosaur from its nest so that others may steal from it only compounds the factors contributing to the continued evolution toward human beings. Constantly having to evade predators who would have evolved the instinct to be wary of the threat to their continued survival presented by these proto-humans leads to their developing nomadic traits, increasing the potential for variation in diet and for acquiring new knowledge as the result of adaptations to changing environments.
The argument will no doubt be made for the fact that it appears that 98% of our genome is similar to the chimpanzee's, therefore we must have evolved from apes. I can counter that in any number of ways. For one thing, it is quite obvious to me that we have closer physical similarities to orangutans than to chimpanzees. Also, when one compares the completely shorn bodies of the great apes the greatest similarity to the human form is in the gibbon, curiously enough because the gibbon is a simian still very much preoccupied with swinging from branch to branch. Furthermore, from the Discover Magazine article (04.04.06) titled The 2% Difference:
"In genomes involving billions of nucleotides, a tiny 2 percent difference translates into tens of millions of ACGT differences. And that 2 percent difference can be very broadly distributed. Humans and chimps each have somewhere between 20,000 and 30,000 genes, so there are likely to be nucleotide differences in every single gene."
Dinosaurs aren't extinct at all. Dinosaurs are our ancestors. We are now human. In fact, considering the impact perpetrated upon our existence as demonstrated by the nature of humanity today, it doesn't disturb me in the least to accept the fact that we have most likely evolved from a sneaky egg-stealing bi-pedal dinosaur-like creature, unique then as now.