Question

Briefly discuss the process of evolution in producing our species, Homo sapiens. What was/were the trend/s in hominin evolution? What role does evolution play in producing human variation? How do we study and attempt to understand human variation? Why?

Answer 1

The origin and evolution of Homo sapiens :some using the classic multiregional concept of H. sapiens , would probably cover the whole Pleistocene history of the human genus, while some are much more restricted ,might require a focus limited to a small set of middle–late Pleistocene fossils. The term H. sapiens for material that appears morphologically more closely related to extant humans than to the clade of Homo neanderthalensis, one of two potentially closest fossil relatives of extant H. sapiens (the other being Denisovans, which are so far virtually unknown from fossil material) . Some researchers, particularly archaeologists, include behavioural factors in their diagnoses of modern humans/H. sapiens, Extant H. sapiens share specific traits such as a high neurocranium, rounded in lateral profile, a small face retracted under the frontal bone, a true chin even in infants, small discontinuous supraorbital tori, a lengthened post-natal growth period and life history, and a narrow trunk and pelvis with short superior pubic rami. Anatomical characterization of the H. sapienslineage should thus be possible from features such as cranial globularity, retrocessive face, basicranial flexion, development of a mental osseum, dental microstructure and pelvic shape . In addition, distinctive morphologies of elements of inner ear anatomy are being increasingly well characterized in H. sapiens. In the cranial vault, the shape of the parietal region in H. sapiens seems particularly distinctive and makes a significant contribution to globularity in both lateral and occipital views. Basicranial flexion is a more complex feature, but H. sapiens certainly appears distinctive in various measurements of this . Dental microstructure, especially with the advent of micro-CT and synchrotron technology, is not only demonstrating the extended ontogeny of H. sapiens, but also revealing clear differences between H. sapiens and other hominin species in features such as enamel thickness and the shape of the enamel–dentine junction.

"An evolutionary trend can be defined as a persistent, directional change in a character state, or set of character states, resulting in a significant change through time.

Different trends in homini evolution:

Bipedalism

Opposable thumbs

Complex thinking

Ability to build tools and weapons

Complex language

Evolution play important role In human variation:

Within the last decade, our ability to probe our own species for evidence of selection has increased dramatically due to the flood of genetic data that have been generated. Starting with the complete sequence of the human genome , which provides a framework and standard reference for all human genetics, key data sets include the completed or near-completed genomes of several related species (e.g., chimpanzee, macaque, gorilla, and orangutan), a public database of known genetic variants in humans, and surveys of genetic variation in hundreds of individuals in multiple populations . With these new data, it is now possible to scan the entire human genome in search of signals of natural selection.

Although the study of natural selection in humans is still in an early stage, the new data, building on decades of earlier work, are beginning to reveal some of the landscape of selection in our species. In fact, researchers have identified many genetic loci at which selection has likely occurred, and some of the selective pressures involved have been elucidated. Three significant forces that have been identified thus far include changes in diet, changes in climate, and infectious disease.

How we study human variation: Human genome project, Human variome project, Human genomic study, Population genetics, social science, social research, Demography, biodemography, bioinformatics, biostatistics, DNA finger printing, single nucleotide polymorphism, RFLP.

Why : The study of human genetic variation has evolutionary significance and medical applications. It can help scientists understand ancient human population migrations as well as how human groups are biologically related to one another. For medicine, study of human genetic variation may be important because some disease-causing alleles occur more often in people from specific geographic regions. New findings show that each human has on average 60 new mutations compared to their parents.