Biological Anthropology: The Natural History of Humankind - Essay Example

Natural selection acts on phenotypes because differential reproduction and survivorship depend on phenotype. If the phenotype affecting reproduction or survivorship is genetically based, then selection can remove genotypes indirectly by removing phenotypes.

ABO blood group systems are blood types A, B, AB, or O in human beings blood types called polymorphism, which is defined as a genetic locus with two or more alleles that occur in large frequency in a given population. ABO blood group is not only a significant blood factor in clinical applications entailing blood transfusions but also proving to be a salient asset for determining human migration patterns and origins. Clinal distributions are generally thought to reflect micro-evolutionary influences of natural selection and/or gene flow. A cline is a gradual change in the frequency of a trait in populations dispersed over geographical space.

Lactose is the disaccharide component in milk. This component consists of glucose and galactose, which are monosaccharides. Lactase is required to digest lactose. The production of lactase production is known to decrease with age, a process that results in lactose intolerance. High concentrations of lactose are found to occur naturally in dairy products as well as in processed food. Lactose intolerance occurs in individuals with low or insufficient levels of lactase, which is an enzyme responsible for the catalysis of lactose. This is a hydrolysis process where lactose is broken down into glucose and galactose in the digestive system.

Adaptability is the ability to rapidly cope with changing environmental conditions, which has made it possible for organisms to survive in most regions of the world.  Acclimatization involves a change in the population of a species. When traveling to high altitudes, our bodies adjust so that there is enough oxygen in our cells. A healthy acclimated person can tolerate extended exposure to virtually any natural weather-related heat stress. Where chronic heat exposure induces a fairly uniform pattern of thermoregulatory adjustments, chronic cold exposure induces three different patterns of adaptation.  The low air pressure found at high altitudes makes it difficult for oxygen to be supplied to the vascular system hence causing high-altitude sickness.

Almost all living primates have prehensile hands and feet, and most have five digits on these appendages. Primates have particularly flexible and limber shoulders and hip joints. Primates have a nail on the first digit. Primates also possess a clavicle or collarbone. All primates tend to be erect. Most species stand on two hind legs like humans. Examinations based on the arboreal hypothesis reveal that claws, which are used as climbing tools, are superior to bare hands, fingernails, and feet. This makes them beneficial for transporting larger bodies through tree branches. About the visual predation hypothesis, stereoscopic vision is used in estimating the distance and size of food sources. Orbital convergence of the eyes results in a condition known as reduced olfaction.

Niche separation between species forms stable mixed species groups to examine the partitioning of resources and how the separation affects the stability of such groups. Ecological theory states that whenever two closely related species having strongly equal ecological requirements occur sympatrically, a lead to interspecific competition that drives one of the two species to local extinction or character displacement. Moreover, primates have intra and interspecific variation in a range of biological traits, which makes the man an excellent reference point for comparative studies that can inform principles of ecology and biogeography and provide insight into such areas as the macroecology of body size, density, abundance,  and geographic range size(Stanford, John, and Susan). 

In polygynous mating patterns, one male regularly mates and lives with multiple females at any given time. This pattern is commonly found among animals such as baboons, monkeys, gorillas, and some human societies. There are some communities, such as those of Hamadryas baboons, which are composed of multiple polygynous families.  In such multiple family and group societies, males are always the dominant and controlling members. The responsibility of the adult males in these societies includes looking after their females and offspring, maintaining order within the community as well as offering protection from predators. In rats, for example, the mother, a strange male or female may be the infanticidal member. Here, mothers tend to kill deformed, weak, or wounded infants hence allowing the mother the chance to allocate resources to healthy infants. This increases the survival chances of the healthy infants in the community. In some cases, mothers may kill entire litters especially when they are stressed. In this condition, mothers perceive the environment as tough for the survival of the young ones hence the decision to kill them. She also gets energy from the consumption of the young ones.