Question

2. What does the decrease in canine size indicate about the probable social grouping of hominids? Think about traits associated with monogamy, polygamy and promiscuity.

3. How do we define a hominid? How does mosaic evolution affect classifying fossils as hominids? Mosaic means having a mixture of traits. For example, Ardi had a mixture of ape and hominid traits.

Answer 1

2)ans: The main distinguishing feature of early hominids is a reduction in the size and projection of the canine teeth. The large canines of most primates are not principally a dietary adaptation, but reflect the social aspects of directly fighting or communicating threats. The reduction of the canine teeth in early hominids likely indicates that these social interactions had changed.One possibility is that social competition, particularly among males, may have reduced in intensity. Such a reduction in male competition is consistent with models of the evolution of bipedalism that involve greater parental investment and provisioning of offspring. On the other hand, competition may have remained strong but may have taken a form for which large canines were useless. For example, the development of weapons such as clubs or accurately thrown rocks would reduce the advantages of large canines. Likewise, the development of more effective vocal communication might reduce the impact of visual signals like the canine teeth. Amid these possibilities, the reasons for smaller canines in hominids remain uncertain, but are clearly linked to the evolution of other features such as bipedality and social complexity.

3) ans: A hominid is any member of the biological family hominidae. These are the "great apes", living and extinct. At present there are humans, chimpanzees, gorillas and orangutans. The word "hominid" has been used in various ways. ... The original meaning of the taxon hominidae meant only humans and their closest relatives.

When paleontologists compare a single ancestral species with a known descendant, there is an expectation that a fossil intermediate in time will be similarly intermediate in all ana- tomical features. However, these different species of hominin do not tell a simple linear story. Each body part has its own history and has evolved at a different pace and sometimes a different direction in each species to produce unique combinations of anatomy”. This is what paleoanthropologists generally call “mosaic evolution”: a differentiated evolution and a “potential independence of trait" combined in different ways from species to species. The term“mosaic” refers here to the description of what we call “hominin morphological instability”, which means specific morphological assemblages or modules evolving independently from each other, in a non-harmonious way and at different rates when compared with other related species. The concept of ‘mosaic evolution’ refuted the notion of harmonious development by affirming that individual organs could have independent phyletic histories, despite the evident correlation of parts within any organism” .