If humans evolved from chimps, why are there still chimps?

If humans evolved from chimps, then why are there still chimps?

Many people think that this is a dumb question, but it is not, it is actually very valid. This is a question that science has not yet come up with a concrete answer for. 

The first thing we must address is the fact that we did not actually evolve from chimpanzees. Humans and chimpanzees both evolved from a common ancestor, so instead of chimps being the "mothers" of humankind so to speak, they are more like cousins to humans. We are closely related, yes, but we have actually been on separate evolutionary paths for around six million years, give or take. Unfortunately, we do not have much information at all on our common ancestor, as fossils have yet to be found. Hopefully, this will change and we will be able to put a face to our ancestor, but for now, we must work with the fossils of early hominids as well as chimpanzee and human DNA. 

Although we did not evolve from chimps, the question still remains: why did we not evolve together? Why did one species evolve to be more complex than the other? Why do humans have bigger brains and bipedal locomotion? 

One somewhat short and simple possibility is that chimpanzees were doing fine just as they were. Perhaps there was just no need for further evolution. Chimpanzees are a highly intelligent group of animals with incredible cognitive mapping abilities, working memories, and perhaps even theory of mind. They have the capability to make, use, and understand tools. Perhaps with the combination of physical and mental capabilities, there was simply no need for further evolution. Going by the Darwinian model of evolution and natural selection, evolution occurs when there is a need for an organism to develop features or habits that will assist in allowing it to thrive in its environment and successfully reproduce. So far, chimps and other apes have been able to thrive in their environments and successfully birth and raise the adorable baby apes that we love to look at so much. 

By saying that chimps had no need for further advancement, it implies that early hominids were flawed. Perhaps they were not as well suited for the environment, encountering things like predators, food shortages, and weather events that prevented them from thriving. In order to preserve themselves, evolution selected to acquire different traits, perhaps even more so when early ancestors began to migrate to different regions of the world. 

Simply put, evolution is not as linear as some people believe it to be, and this is why things such as cladograms exist. I like to think of evolution in terms of a neighborhood. We begin with the entrance to the neighborhood, which represents one of the oldest common ancestors or organisms, Then, every street within the neighborhood is a different evolutionary lineage, and every house on that street a different organism or family of organisms. 

Hopper, L. M. & Brosnan, S. F. (2012) Primat Cognition. Nature Education Knowledge 5(8):3

Warren, Kerryn, et al. “Early Hominins.” Explorations: An Open Invitation to Biological Anthropolgy, American Anthropological Association, Arlington, VA, 2019, pp. 2–56.