The Most Appropriate Characteristics To Define Which Species Should Be Included In The Genus Homo

When considering the most appropriate characteristics to classify a species, we must think about what it is to be human. First of all, it would seem wise to use genetics – any code closely matching our own could surely be classified as human, so determining whether an organism is genetically related enough to be in the same genus. However, it has been seen in research, such as that on brain development, that one small change in the DNA, one that may not initially make us classify an organism differently, can make a very different species altogether. One change in the DNA can cause a huge cascade event down the whole genome. Therefore, it would not be entirely wise to use this characteristic as a main method of identification without using more appropriate ones first.

A more appropriate characteristic would be morphology – in particular, the indicators of locomotion. Looking at data on the humero-femoral index of several fossil hominids, we can conclude that any organism that has an index between 70 and 80/90 has the capacity to be bipedal: a key Homo feature. The closer to the modern human the organism is, the closer to 70 this number will be, and so the more bipedal. This characteristic is useful, as it can be used quite reliably over the hominids, if not over other organisms too such as the Felis species shown in the table.


Another characteristic appropriate for defining which species should be included in the Homo genus is speech and communication, a quality often attributed to complex, usually human, societies. Speech is not necessary for understanding, but it does improve the information transmission, meaning that previously unexpressed ideas can be expressed. For example, hunting, description of hazards and swapping stories all benefit from speech and language, a characteristic unique to the Homo genus, so one that is appropriate to define which species belong to the genus.

Lastly, the third most appropriate characteristic for defining the genus Homo is sociality and altruism. While both different things, they are often closely related: there has to be a society for altruism to exist. Humans, members of the genus Homo, are highly social, highly adaptive, and show relationships in society. While this is not totally unique to the genus, it is a good character to use in classification as we can assess the degree of sociality: humans are often regarded as ultra-social, and the only genus to demonstrate true altruism. During experiments on altruism, it has been demonstrated that humans do indeed show more altruism than other species, and an unselfish concern for the welfare of others, even those they do not know. It allows social cohesiveness, increasing the sociality of the group, which can be seen by the extent of relationships and the appearance of things such as religion – a feature only seen among humans.

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