Why Did Humans Evolve to Have Such Long Childhoods Compared to Other Animals? — Here’s What Experts Say

If you think about your childhood, it may seem like it was such a short amount of time, but compared to other animals and primates, Homo sapiens kids take a long time to grow up. In the animal kingdom, most species are often ready to face the world faster; they can walk earlier and hunt sooner.

However, for humans, their children have a long dependency period on parental care to survive. They take years and years to learn how to eat by themselves, walk, grow up to reach adult size, and reproduce. But why did our species evolve to be this way? Let’s look at what experts say and what this long childhood really means for our lives as human beings.

Big Brains Need More Time

One reason why humans have long childhoods is the complexity and size of our brains. At birth, the brain has not yet finished growing and developing. It means humans do not possess all the capabilities of adult brains yet, as parts of this organ still grow slowly after being born.

There are many reasons for this phenomenon, and one of them is that the brain, as an organ, is one of the most metabolically expensive to grow and maintain. It takes a lot of energy and nutrients.

In other words, when human children are growing up, their body’s resources are being largely diverted to the brain, which could slow down the overall growth of other body parts compared to other animals. This results in a more extended period of needing parental care.

Additionally, there are parts of the brain that could only be developed by exposure, such as the regions that are involved in social skills, self-control, language, and memory. To develop these cognitive and social abilities, a human child would need experience with people, different cultures, and the rest of the world. These are necessities for life that could not be learned in a matter of months, so our species evolved and adapted to have such long childhoods to make time for all of these developments.

Read more: American Scientists

Learning Skills, Culture, and Social Life

Why Do We Have Such Long Childhoods?

It was mentioned slightly above that there are skills that human kids need to learn in order to be ready for the challenges of life. Our species does not just need to know how to walk or run; instead, for most of our evolution, our young also need to learn language, tools, how to hunt or gather, how to cooperate with others, how to make fire, and how to use shelter. All of these skills take time, even in the modern world with our advanced brains.

Homo sapiens also pass down their knowledge and culture to their young. This is one of the key traits that made us so successful in our evolution as a species. Instead of starting from scratch, our young ones were taught to observe, practice, and copy grown-ups. If we evolved to have shorter childhoods, there would have been less time to learn and build upon the last generation’s knowledge and experiences.

Another key survival strategy of humans is their sociability. Millions of years ago, ancient homo genus species were slower, lighter, and weaker. So one of the evolutionary adaptations we learned was to stay and work together. By living as a group, early humans increased their chances of survival.

However, this meant that we needed to know how to be social and get along with other individuals in the group. Longer childhoods would also help in learning these important skills, especially in ancient times, where being thrown out of your group usually meant less chance of survival. So, a longer period before maturity gives space for both emotional and social skills.

Dependence and Protection: Why Kids Stay Protected

Humans have one of the most parentally dependent children in the animal kingdom. When our kids are born, they cannot get food reliably, can’t defend themselves against predators in the wild, and overall just can’t take care of their own safety as individuals.

They rely on parents and the group to which they belonged until they have developed brains and bodies that will make them capable on their own and contribute to the whole group, for everyone to have higher chances of survival.

A long childhood may have been necessary for kids to know how to survive in an environment that is full of dangers like predators, climate change, and competition. Human adults needed to pass on their knowledge and experiences by guiding, communicating, and showing the children directly.

They need to know which plants are safe to pick, where to find the water sources, and how to avoid being hunted by larger predators. All of these skills need time to learn. However, most of these are features of our species that are the result of a few evolutionary trade-offs rather than the primary reason for a longer period of childhood.

Read more: UChicago

Costs and Trade-offs: Why This Strategy Is Special

Growing Up Human: The Evolution of Childhood - Brenna Hassett

The evolution of having a longer childhood in the human species is believed to be an evolutionary trade-off of a few of our survival strategies and adaptations. First, there is the development of bigger brains. The increasing size of our ancestors’ brains meant that the infants would also have bigger heads.

However, we also evolved bipedalism, which was thought to have shaped the pelvis to support the upright walking skills. But this led to a birth canal that was narrower than in other primates, which meant that the human infants had to be born earlier at a less developed stage compared to other primates.

This state is commonly referred to as altriciality, which refers to being born underdeveloped relative to others. In contrast, the opposite phenomenon is called precociality, where the infants are born much more developed, like horses and giraffes, whose young are almost immediately capable of standing and even walking after birth.

Author's Final Thoughts

Humans evolved to have longer childhoods mainly as a trade-off for our successful evolutionary adaptations. Our ancestors developed bigger brains that allowed them to make tools, have complex cognitions, communicate and cooperate socially more efficiently, and more. They also evolved to walk upright to be able to hunt for food and gather resources much better in the open savannas, and a few other evolutionary benefits.

In other words, we may have evolved a longer childhood because it was necessary for us to become smarter, more social, and capable learners to have a high chance of survival in the ancient world. If it weren’t for our long childhoods, we may not have had languages, tools, culture, art, or science. That long amount of time for learning and developing is what made us unique as a species.

Read next: Which Predator Species May Have Preyed on the Early Humans Over 2 Million Years Ago? — Here’s What Researchers Discovered

References & Further Reading

Bogin, B. (1997). Evolutionary hypotheses for human childhood. Yearbook of Physical Anthropology. https://deepblue.lib.umich.edu/handle/2027.42/37682

Leigh, S. R. (2001). Evolution of human growth. Evolutionary Anthropology. https://os.pennds.org/archaeobib_filestore/pdf_articles/EA/2001_10_6_Leigh.pdf

Leigh, S. R. (1996). Evolution of human growth spurts. American Journal of Physical Anthropology. https://pubmed.ncbi.nlm.nih.gov/9016361/