According to research published in Current Biology and reported by New Scientist, Neanderthal babies didn’t just have some minor differences from their human counterparts. They were completely different in a variety of ways, one of which was that they were big as f—k.

The centerpiece of the research is a remarkably complete infant skeleton known as Amud 7, discovered in Israel and dated to roughly 50,000 years ago. Based on its tooth development, the baby was about six months old when it died. But the rest of his body indicates this thing was friggin huge, for an infant, at least.

Its bone length, limb proportions, and overall size were closer to what you’d expect from a modern human that was 12 to 14 months old. This was a baby that was only half a year old, but it was built like a toddler.

Neanderthal Babies Were Surprisingly Huge, Scientists Say

Once researchers compared Amud 7 to two other Neanderthal child specimens, such as those found in Syria and France, they found a similar pattern: the teeth suggest one age, but the rest of the body suggests another. In the minds of these researchers, this can only mean that Neanderthals grew faster in early life than Homo sapiens.

Their development seemed to follow a different pattern entirely, meaning they were just oversized versions of Homo sapiens toddlers. Early on, their bodies and brains experienced explosive growth; the same cannot be said of their dental growth, which lagged. Later on in childhood, however, things started to even out. By around age 7, their growth trajectory started to more closely align with ours. By adulthood, they ended up roughly similar in size, just a bit stockier and shorter on average.

As for why Neanderthals experienced an early growth spurt that outpaced our own, the leading explanation is that environmental pressures from living in colder Eurasian climates fostered faster early growth as a survival strategy, helping Neanderthal youngins bulk up enough to survive the cold.