ELI5: Explain Like I'm 5

Cranial evolutionary allometry

So, you know how some animals have really big heads and some have tiny heads? Well, cranial evolutionary allometry is a big science-y word that helps scientists understand why animals have different sized heads.

It's kind of like when you have a big brother or sister and they are taller than you, so their head is bigger too! Same thing happens in the animal world. Some animals have bigger bodies and therefore bigger heads, while others have smaller bodies and smaller heads.

Scientists use a lot of math and measurements to figure out how the size of an animal's head compares to the rest of its body, and they can use this information to learn more about how the animal evolved over time.

So basically, cranial evolutionary allometry is just a fancy science way of explaining why some animals have bigger heads than others, and how scientists can use that information to learn more about how animals have changed over millions of years.