Unraveling the Truth: Do Humans and Chimps Really Share 99% of Their DNA?

Chimpanzees and bonobos are our closest living relatives. It’s often said that humans and chimps share about 98.8% of their DNA. But what does that really mean? Is it accurate?

Experts warn that this number oversimplifies the truth. When comparing our genes, scientists look at the basic building blocks of DNA: adenine (A), guanine (G), cytosine (C), and thymine (T). David Haussler from UC Santa Cruz explains that comparing DNA is like looking at two versions of a very long book. While some chapters match closely, others differ significantly.

Katie Pollard, a researcher at the Gladstone Institute, clarifies that around 1 in 100 nucleotides (the parts that make up DNA) differ between humans and chimps. For context, humans share about 99.9% of their DNA with each other.

However, that figure of 98-99% similarity is misleading. It mostly highlights parts of DNA that align well, ignoring sections that don’t. Tomas Marques-Bonet from the Institute of Evolutionary Biology notes that about 15% to 20% of the human genome lacks a clear chimp counterpart. This includes DNA that is unique to one species, known as insertions and deletions.

A 2025 study even suggests that the difference between human and chimp genomes could be closer to 15%. This study highlights that genetic variation among chimps can be significant, with differences reaching up to 9% within their species.

Despite these findings, our genetic closeness remains. Martin Neukamm, a chemist from Munich, emphasizes that while differences exist, the close relationship stands firm. Most of these genetic differences lie in noncoding DNA, which doesn’t directly create proteins but regulates how and when genes are expressed.

Marques-Bonet points out that these regulatory regions act like light switches for our genes. Small changes can lead to significant differences in traits. For example, how genes express themselves might determine if an individual is tall or short, or has more or less body hair.

In summary, while chimps and humans share many genetic similarities, the differences—especially how we use our DNA—can lead to big variations in traits. So, yes, we’re closely related, but it’s the way our genetic “building blocks” work together that shapes who we are.

For more on the genetic similarities and differences between humans and chimpanzees, you can visit Live Science or check out the study findings on Gladstone Institute.

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