Are Humans Part of the Ape Family? Exploring Our Evolutionary Journey

Humans naturally seek connections to themselves, whether it's recognizing familiar traits in animals or imagining human forms in the stars. This explains why we look at gorillas and chimpanzees and see glimpses of our own nature: the wild, the pure, and the endearing.

So, do humans belong to the ape family?

Scientifically speaking, the answer is a definitive yes. Humans and apes are closely linked as part of the primate family, sharing a common ancestor from 5-6 million years ago and a genetic similarity ranging from 94 to 99 percent. The bond between us goes beyond superficial likeness, raising the question: why are we the ones observing from outside the enclosure?

Great Apes and Human Origins

In modern biological classification, apes are divided into two primary categories: lesser apes and great apes. Humans fall into the great ape category, along with orangutans, gorillas, bonobos, and chimpanzees, while gibbons are classified as lesser apes.

Approximately 17 million years ago, the great apes diverged from their evolutionary relatives. Between 200,000 and 300,000 years ago, Homo sapiens appeared, marking the beginning of the species' gradual rise to global prominence.

What truly distinguishes this unique branch of life? Physically, apes are almost superhuman compared to us. For instance, chimpanzees are approximately four times stronger than the average person [source: ScienceDaily].

Although humans don't match the raw strength of chimpanzees, our nervous systems provide greater control over our muscles, allowing for more precise and delicate movements. Humans excel in motor skills, have less body hair, and possess a significantly more developed brain.

Neuroscientists have discovered much more complex neural connections in the human brain, including specialized cells known as spindle neurons. These Von Economo neurons (VENs) are predominantly found in brain regions linked to social emotions.

Why Did Apes Stop Evolving?

The term "social emotions" encompasses a wide range of human traits, such as empathy, guilt, and shame. While humans have evolved socially since our last shared ancestor with chimps, other nonhuman primates have remained relatively unchanged.

Humans and chimpanzees still share certain primal traits, such as male kinship bonds and aggressive territorial behavior. However, human males and females often form stronger marital bonds, leading to family-oriented societies. In contrast, chimpanzees maintain distinct male and female hierarchies.

These distinctions often stem from minor genetic variations. Although humans and chimps have similar gene sequences, copy number variations can vary significantly, involving repetitions, deletions, and reversed sequences. To simplify, consider human names: "Jim Morrison" differs from "Jim Jim Morrison," "Morrison Jim," or the anagram pseudonym of The Doors singer, "Mr. Mojo Risin."

In humans, copy number variations can differentiate identical twins and are linked to various diseases, including AIDS [source: Fox]. Essentially, it's not just the genes themselves but how they are expressed that matters.

Why Are Humans Classified as Apes?

As scientists continue to explore human evolution, the undeniable link between humans and apes remains a key foundation. Below are some reasons for our shared classification:

Primate Evolution: Climbing the Tree of Knowledge

Researchers suggest that a surge in genetic changes 17 million years ago caused the great apes to diverge from lesser, tailed primates. Later, between 4 to 7 million years ago, another genetic shift led to the separation of humans from other apes.

By analyzing genetic differences between humans and other apes, scientists at Cornell University proposed that the split between humans and chimps may have been influenced by differences in sensory perception, particularly scent and taste [source: Cornell News].

The Cornell research team identified numerous gene sequence alterations in areas linked to smell, digestion, and other functions. Humans are undoubtedly the most advanced primate species globally, with chimpanzees ranking second.

A similar hierarchy emerges when examining meat consumption among primates. Chimpanzees are second only to humans in this regard. Scientists propose that dietary shifts triggered by abrupt climate changes may have been the primary driver of the evolutionary divergences that separated humans and chimps from their last common ancestor.

The genes in question also influence long-bone development, body hair, and hearing—the latter being closely tied to the evolution of speech. Increased meat consumption may have also reduced physical disparities between males and females.

Primatologists suggest that a new mating system arose in humans around 1.9 million years ago, replacing the separate male-female hierarchies with a more collaborative approach. As males shared more meat with females, the latter grew larger and were able to bear bigger offspring with more developed brains.

If these findings hold true, it implies that humanity's appetite played a pivotal role in its evolutionary journey toward global dominance—a relentless drive that continues to influence the future of all life on Earth.

Ape Talk: Where Human and Primate Communication Intersect

A study published in PLOS Biology highlights that great apes utilize more than 80 distinct gestures for everyday communication. These include actions like the "big loud scratch," used to ask for grooming, and the "object shake," which can convey requests for closeness or instructions to relocate.

Chimpanzees and bonobos, our closest relatives, share over 90 percent of their gestures, potentially shaping the development of human language. Researchers observed that human infants employ more than 50 gestures strikingly similar to those used by apes.

In the study, over 5,600 participants viewed online videos of ape gestures and correctly interpreted their meanings with over 50 percent accuracy. This ability points to an innate understanding of primate communication, though the precise mechanisms behind this skill require further investigation.