The human being is an intellectual slave to the great questions that have been asked since he has been able to remember: where do we come from? where are we going? His search is, deep down, what motivates all the science that makes the planet we live on spin.

Perhaps one of the basic answers to such questions lies hidden in the earth we walk on, compacted under the sediments of time, eluding the naked gaze of those who wander about it without questioning who they are or why they are alive and breathing.

The fossils, stony bones that give silent testimony of what we once were, scream at us about the very nature that we harbor in our genetic code. For this article, we will take a journey back many thousands of years, in order to meet someone closer than we think: Homo erectus .

Discovering the Homo erectus

The Homo erectus (“standing man”) belongs to the genus Homo , which describes a subgroup of bipedal primates with a skeleton and a nervous system designed for upright walking, and among which is the current human being ( Homo sapiens ). As for Homo erectus, it is known that it lived until approximately 70,000 years ago, although its origin dates back a long time (about two million years).

His first fossil remains were found on the island of Java (Indonesia), and for that reason he was named the “Java man”. At that time it was determined that he must be a species of primate without any connection to modern humans, since the perimeter of his cranial vault did not allow us to infer that the development of his cognitive abilities was even remotely close to ours. It was, therefore, labelled under the scientific nomenclature of anthropopitecus erectus, although as more details were discovered about it, its name was modified until it received the name by which it is known today.

With the passage of time it has been discovered that the fossil remains of Homo erectus can be found in many geographical regions of Asia and Africa, so it follows that was the first being able to move far beyond the place where all his ancestors took root (East Africa) . This evidence, along with others which will be detailed throughout the article, was the first to suggest that he may not have been just another ape: but that he could have been one of the closest hominids to what we are today, an adventurer from prehistoric times.

What did he look like?

It is important to note, first of all, that Homo erectus was a species that showed great anthropometric variability, reaching the point of confusing the scientific community for decades (considering that the remains found could actually belong to two or more different animals). All this also extends to the discrepancies between males and females (sexual dimorphism), as they were more pronounced than in present-day humans . For this reason, this article will discuss the average traits in individuals of the species.

Today we know that the arrangement of his spine and skull allowed him to move in a bipedal manner, being equipped with feet whose bone organization is suggestive of the ability to walk upright (hence the name with which it was baptized) and even to run long distances and hunt while maintaining the same position. He lived on the ground, and not on trees, at least from what can be deduced from his bones.

The remains found in Africa are undoubtedly much smaller than those found in East Asia; in fact, they even received a different name ( Homo ergaster ) which is still in use today. This implies, of course, that their skulls were also very different. This enormous variability is undoubtedly one of the distinctive features of Homo erectus and one that has generated the greatest uncertainty for those who dedicated their lives to understanding it as a unified species.

Determining the size of the brain is essential for the knowledge of the intelligence of every living being, since the proportion that is determined for its relative weight (with respect to that of the body), is the most used and reliable index to make an estimate in this respect. In the specific case of this species of human , skulls have been identified with a volume between 700 and 1100 ml , which places them above the gorilla (600 ml) and close to the human (1200-1500 ml). The current average is estimated to be 940 ml, inserted in a very low cranial vault that gave it a remarkable capacity for development.

The Homo erectus was also a large and corpulent being, having agreed that its height could reach 1.80 meters, although it would depend on the conditions in which they lived (resources, climate, etc.) and the presence or absence of some natural predator. They had a strong jaw without any chin, with smaller teeth than those of other hominids with which they came to live in African territory (like the Homo habilis or the Homo rudolfensis ).

Both brain and physical size have long been used to explain how they came to be dispersed on this planet, for they necessarily had to go into inhospitable terrain to reach East Asia from the African continent, which required strength and intelligence. It has been estimated that their capacity to adapt to the environment was very similar to that of today’s human being , despite the fact that in this sense there are still many unknowns that remain unanswered.

What were his habits?

The Homo erectus was, without a doubt, an animal with a tendency to gregariousness. It lived in small groups of around 30 individuals and had a series of differentiated roles that gave the community a clear sense of hierarchy. Its social organization was much more rudimentary than that of the current human being, who required the experience of a cognitive revolution to be able to support the coexistence in big cities, but it is a valuable sample of how communality was lived in primitive times.

A very interesting fact about this hominid is that he probably was very familiar with fire, and he even used it as a tool to prepare a diet based on meat (as inferred from the bone hypervitaminosis which is usually obtained in the mineral analysis of his femurs), something which contributed to his enormous brain and technological development. The fact is that they could also use (lithic) weapons and various instruments, for which we can see an increasing sophistication, and which allowed a survival that extended far beyond that of the contemporary homo.

As it could not be otherwise, they achieved access to meat through hunting, for which they organized raids in which they showed great capacity to collaborate in the achievement of a shared purpose. It is also believed that they could prey on those who competed with them for vital resources, or if necessary, join forces with nearby tribes to prey on a larger animal (after which they tended to disperse again). They also acted as scavengers, feeding on the carcasses that other animals left behind.

Although it is highly doubtful that this homo was capable of producing an articulated language with which to share “symbols” of a verbal nature, it is known that they employed trade (without currency) with like-minded tribes, exchanging the resources necessary for their survival . It is also very likely that the females of each of the groups were involved in this process and that they became products of trade in order to increase reproductive capacity and reduce the harm of inbreeding.

Why did it become extinct?

The reasons why a species becomes extinct are always diverse, complex and even controversial. In the case in question, it is clear that they had to go through a particularly difficult climatic period, in which they began to lack the resources they had available to satisfy the most basic need of their bodies: food. And perhaps all this could have happened after the great volcanic eruption of Toba.

This happened in the same period for which the end of Homo erectus is estimated (about 70,000 years ago), in northern Sumatra (an island in Indonesia), and meant a severe volcanic winter that reduced the population of primates and hominids . This moment is contemplated, in numerous scientific publications, as the most relevant milestone to explain the extinction of many of the species that at that time inhabited the earth, as it meant dramatic changes in the flora and fauna they needed for their subsistence.

This incident caused the population of Homo erectus (and other species) to be severely decimated, with about 90% of the total individuals and breeding pairs lost. It is now known that the areas near the sea shores suffered less from the ravages of the volcanic winter (a dense layer of dust that prevented vegetation from growing globally for about five or six years), as there are sites very close to those of such an incident that were affected, but where Homo erectus was able to continue his life with absolute normality (thanks to the abundance of fish).

There are also several recent studies that point to the hypothesis that, for as yet unknown reasons, Homo erectus may have begun to neglect the processes through which it made its weapons and tools . This is deduced from the fact that they used precarious materials for them, deciding not to move to relatively close locations where they could have provided themselves with better raw materials, settling for poor manufacturing that could have reduced their efficiency in hunting and other activities.

These fundamentally theoretical and as yet uncorroborated models would suggest that “laziness” was a contributing factor to the extinction of a species that harboured the potential to survive the calamity that was its due. In any case, on the day the Lake Toba volcano erupted, humans faced what was undoubtedly the most tragic page in their long natural history.

Bibliographic references:

  • Baab, K. (2015). Defining Homo erectus. 2189-2219. doi: 10.1007/978-3-642-39979-4_65.
  • Carotenuto, F., Tsikaridze, N., Rook, L., Lordkipanidze, D., Longo, L., Condemi, S. and Raia, P. (2016). Venturing out safely: The biogeography of Homo erectus dispersal out of Africa. Journal of Human Evolution. 95. 1-12. doi: 10.1016/j.jhevol.2016.02.005.