In 2017, actor-comedian Tim Allen famously tweeted a question that revealed just how little he understands about evolution. It seems he’s not alone. His tweet got almost 50,000 “likes” and 13,000 retweets. It’s safe to assume a lot of people reacting to Allen's post also wanted to know the answer to the question that he posed as a statement: “If we evolved from apes why are there still apes.”
The short answer is that "we didn't evolve from any of the any animals that are alive today,” says Zach Cofran, an anthropologist at Vassar College. That is to say, humans didn’t evolve from the gorillas we see at the zoo or the chimpanzees we snap pictures of on a safari. “It's a common misconception that apes are a step away from becoming human or something like a step along the way,” says Cofran. But, he adds, that’s not the case.
Charles Darwin, the naturalist best known for his theories of natural selection, described evolution “as ‘descent with modification,’” says Cofran. That means humans descended from common (and now extinct) ape ancestors that lived millions of years ago, a process also referred to as “common descent." While we share our ancestry with these animals, along the way, over millions of years, we all changed. "[We] each adapted to our own environments or specific circumstances or niches,” says Cofran. It’s believed that this human divergence from the chimpanzee lineage of apes happened between 9.3 and 6.5 million years ago.
The bottom line is that all humans are apes and, as such, all humans are related to other apes. This concept of universal relatedness is “actually very humbling because when you think about it, we share ancestors with pretty much everything that's alive on earth," says Cofran. In other words, we are all descendants of a single species that lived millions and millions of years ago. It also means humans are related to whales, sharks, trees, earthworms and bacteria.
“A lot of the genetic stuff that makes us what we are is the same stuff that makes other animals what they are," says Cofran. "It just kind of gets deployed differently.” In short, we talk about apes the most when we talk about evolution because they are our closest living relatives today.
Still Evolving
Cofran points to another common misconception — namely, that humans are not evolving anymore. But all animals on Earth are continuing to evolve, and that means humans are, too. Plus, he continues, we tend to view evolution through a human-centric lens: The goal of evolution is not to become human, and a creature that looks more “primitive” isn't on a path to one day becoming human, either.
Read more: Human Evolution in the Modern Age
"[We are not] the pinnacle of evolution,” says Cofran. "It's a misconception to believe that everything is evolving towards humanity.” In fact, he says, evolution doesn't really have a goal. "As a society, we’ve imbued the term evolution with a lot of social baggage, where we kind of think of evolution as some kind of improvement.”
Branching Trees
Some researchers think we need to rejigger the way we visualize evolution, and the terms we use to explain it. Another misconception is that evolution is a strictly linear process — that is, it occurs in a straight line from primitive to advanced. But it may be more accurate to think of evolution as a "branching" process. The scientific term for this branching is cladogenesis, or the creation of a new group of organisms through "evolutionary divergence" from that shared ancestor. In other words, cladogenetic events are when one species “splits” into two. And those moments are the key to evolution.
Still, that doesn't mean that thinking of evolution in linear terms is entirely without merit, argues Ronald A. Jenner, a biologist at London's Natural History Museum, in a 2018 paper. "Influential voices have misled audiences for decades by falsely portraying the linear and branching aspects of evolution to be in conflict," writes Jenner, adding that these portrayals often don't distinguish between the (legitimate) linearity of common descent and the branching relationships that result when lineages of common ancestors diverge.
Top-Down vs. Bottom-Up
It's important to note that even those who study evolution don’t always agree on how to best approach it. Evolutionary biologists with the American Museum of Natural History (AMNH) in New York City highlighted the different tactics in a 2021 paper published in Science. The scientists present two main approaches to studying and understanding human evolution: "top-down” and "bottom-up." The top-down approach, fittingly, relies on the analysis of living apes like chimpanzees, while bottom-up focuses on the fossils of mostly-extinct apes. In the Science article, the researchers argue that these fossil apes can provide key information about ape and human evolution.
Study author and AMNH biological anthropologist Ashley Hammond thinks that scientists can't get the whole picture of evolution without looking at both approaches. "Living ape species are specialized species, relicts of a much larger group of now extinct apes," she said in a press release. “When we consider all evidence — that is, both living and fossil apes and hominins — it is clear that a human evolutionary story based on the few ape species currently alive is missing much of the bigger picture."
Beyond that, added study author and AMNH biological anthropologist Sergio Almécija in the press release, conflicting theories about ape and human evolution would be much more complete if more of these extinct species were part of the equation. “In other words, fossil apes are essential to reconstruct the ‘starting point’ from which humans and chimpanzees evolved.”
In fact, the recent discovery of an ape fossil — a tooth, in addition to flint points thought to be the tips of arrowheads — in a cave in southern French pushes back the earliest date of our species in Europe by about 10,000 years, to roughly 54,000 years ago. The find suggests that modern humans lived alongside Neanderthals, something scientists had long suspected but never established until now.
