At first glance, the X-ray images of a baby gorilla and a human infant could almost be mistaken for one another. Both have rounded skulls, small rib cages, and tiny, curling fingers. But look closer and you’ll spot the feature that sets the two apart: the gorilla’s noticeably longer arms.

Close Genetic Ties Reflected in Bone Structure

Scientists say the similarity is no surprise. Humans and gorillas share about 98% of their DNA, and both belong to the great ape family. According to primatologists, these shared genetics show up clearly in early skeletal development.

“Newborn gorillas and humans are more alike than different,” said anatomist Dr. Susan Larson of Stony Brook University. “The main distinctions emerge as gorillas adapt to life in the trees and on the ground, while humans adapt for upright walking.”

Key Differences Start Early

Even at birth, baby gorillas display arms longer than their legs — an evolutionary adaptation for climbing and knuckle-walking. Their skulls also show subtle forward growth of the face and jaw, a feature that becomes more pronounced as they mature. Human infants, by contrast, have rounder heads and shorter arms relative to their legs, preparing for eventual upright posture.

Why the Comparison Matters

Experts say understanding these skeletal parallels is important for both evolutionary biology and veterinary medicine. Comparing bone development helps scientists track how humans and great apes diverged from a common ancestor millions of years ago. It’s also valuable in zoos and sanctuaries, where veterinarians use human pediatric knowledge to inform the care of baby apes.

“Seeing the likeness helps people realize how close we really are to other primates,” said Dr. Larson. “It’s a reminder of our shared evolutionary history.”

A Visual Lesson in Evolution

Images like the one circulating online — showing X-rays of a baby gorilla beside a human baby — have gone viral, sparking curiosity and conversation. While the comparison is simplified, the science behind it is solid: baby gorilla skeletons are strikingly similar to those of human infants, with proportionally longer arms being the key visible difference.