Question

B) What is one trait that Shkul V has that is shared with ancestral hominins? What is one trait that is a derived feature of modern humans?

Ancestral)

Derived)

Answer 1

Hominin – the group consisting of modern humans, extinct human species and all our immediate ancestors (including members of the genera Homo, Australopithecus, Paranthropus and Ardipithecus).

Why have these changes occurred?

‘Hominid’ and ‘hominin’ are derived from names used in the scientific classification of apes (including humans). By international convention, certain word endings are used for specific taxons or levels within this classification. For example, ‘family’ names always end in ‘-idae’ (eg Hominidae), ‘subfamily’ names end in ‘inae’ (eg Homininae) and ‘tribe’ (1) names end in ‘ini’ (eg Hominini). These formal names are then abbreviated to give the common names hominid, hominine and hominin respectively.

The name changes that have occurred have arisen due to changes in the way humans, chimpanzees, gorillas and orang-utans are classified. For example, it was once thought that apes should be divided into three different groups (families). In this old scheme, humans were seen to be so different to other apes that we should be placed into our own distinct family, the Hominidae or hominids.

Over time, biological classifications change due to improved techniques and better knowledge about the biology and the evolutionary relationships of different living things. Now, with their better knowledge, scientists have revised their classifications to develop more up-to-date evolutionary trees. In this scheme, only two families are recognised with all the Great Apes (including humans) placed into the same family, the Hominidae or hominids. The next branching of this evolutionary tree divides the orang-utans into one subfamily and all the remaining Great Apes into another subfamily. Then at the tribe level, gorillas, chimpanzees and humans separate onto different branches of the evolutionary tree with humans in the Hominini or hominin branch. As a result of this classification change, modern humans and all our extinct ancestors on our own branch of the evolutionary tree are now known as hominins rather than as hominids as they were formerly known in old classifications.

TRAITS WE MIGHT POSSESS IN MODERN HUMANS

Humans of the future may have less hair

Humans are already commonly referred to as the hairless ape. Of course, this is a facetious title; like all mammals, humans do have hair. But it's true that we have much less of it than our ape cousins, and likely much less of it than our hominid ancestors did too. In fact, Darwin, in "The Descent of Man," considered body hair to be a vestigial structure in humans.

Clothing, along with modern technology such as air conditioning and heating, has made the insulating properties of body hair obsolete. Although the evolutionary fate of body hair can be particularly difficult to project because it can also act as a signifier for sexual selection (i.e., body hair can be viewed as physically attractive, and thus be perpetuated within a population), it is likely that humans of the future will have much less body hair than they do today.

Humans of the future may lack wisdom teeth

Most people think of their wisdom teeth as a pesky medical annoyance — those things that must be surgically removed before they start to erupt. The main reason they must be removed is because many modern humans have jaws too small to contain them without disrupting the other teeth. The common postulation is that they are vestigial molars that originally evolved in ancestral humans when our jaws were bigger and our diets included hardier plant material.

So it's not a surprise that wisdom teeth are beginning to disappear. In fact, 35 percent of people are already born without wisdom teeth. Many others are born with just one, two or three wisdom teeth. When a trait is no longer necessary, evolution tends to favor the elimination of that trait to save on the unnecessary energy expenditure it takes to develop it. Thus, humans of the future may lack wisdom teeth entirely.