Introduction
In her article, Ann Gibbons analyzes the issue of long human childhood compared to chimpanzees, our nearest relatives among all the living beings. She provides the history of discoveries of ancient human remains and the results of their analysis. Additionally, the author provides different reasons why humans start reproducing later than any other species.
First Discoveries
The author claims that according to the analyses of the earliest findings of human remains dated three million years ago, their childhood was shorter and they started reproducing earlier than Homo sapiens. In 1925, Raymond Dart, an Australian anatomist found an australopithecine whom he called the Taung baby. He analyzed the remains and found out that this child died two million years ago at the age of six already having its first permanent molar. He came to the conclusion that early hominins had the same schedule of maturation as modern humans do.
A New Theory
However, Dart’s theory considered true for sixty years until in 1984, in London, anatomists Timothy Bromage and Christopher Dean found a new method to determine the age of fossil children. They analyzed the australopithecine children’s teeth and found out that they had their first molar at the age of 3.5 years old, which is similar to the modern chimpanzee pattern. This discovery gave rise to the question of why our ancestors developed such a risky strategy as a delay of reproduction.
Homo erectus
The analysis of a fossil child, a representative of Homo erectus, who died at the age of eight 1.5 million years ago in Kenya, showed that it had much more similar features with modern humans. However, with his weight of 50 kilograms and height of 163 centimeters, he was too big for an eight-year-old boy. Therefore, having conducted additional analyses, scientists found out that in general, H. Erectus was an intermediate stage of human development, as its brain grew before birth which is similar to a modern human, whereas, in its childhood, it grew up faster which is similar to an ape.
Homo antecessor
In 1999, several fossil children of an H. antecessor who died in Spain 800,000 years ago were analyzed. According to the initial results based on the analysis of teeth eruption, the maturation process of this species was similar to a modern human. However, later results refuted this theory.
In 2007, scientists analyzed an eight-year-old fossil child, one of the first representatives of H. sapiens species, who lived 200,000 years ago in Ethiopia and found out that it had already extended the time of maturation.
Neanderthals
The researchers found out that humans began extending the time of their maturation between 800,000 and 200,000 years ago. Therefore, they analyzed the process of growing a fossil Neanderthal that lived in Belgium 500,000 years ago and found out that it also grew up faster than a modern human do. Thus, anthropologists confirmed that only H. sapiens began extending their maturation.
Reasons for Delaying Reproduction
The first reason for this is the reduction of mortality rates which allows life span and growth to extend thereby delaying reproduction. The evidence shows that mammals that have a low risk of dying young benefit if they reproduce later, as they become stronger and have a bigger chance to protect their babies. Another reason mentioned by the author is an extended family with grandparents who help a mother to raise her child. Thus, this is a principal difference between humans and apes that cannot provide grandparents’ care. Therefore, late maturation is perfect for humans, as we have culture and society that other primitives do not have.