What is Natural Selection?

Biological anthropology is the broadest of the four subfields of anthropology, and it is the field that is most concerned with the biological evolution of the human species.  One of the underlying concepts of evolution is the concept of natural selection, which Charles Darwin put forward in his pivotal publication, The Origin of Species.  You may have heard of this concept, but do you really know what it means?  This blog post will explore what specifically natural selection is and its effect on evolution.

Before we jump into what natural selection is it is important to discuss what it is not.  It’s not some being, such as Mother Nature, choosing who lives and who dies.  It’s not even individuals deciding who will live and dies.  This could be artificial selection, the deliberate breeding of species. 

Natural selection is random, but it’s based on a series of natural factors that unknowingly select individuals within a species that are considered best to survive.  This selection is based on our individual genetics, or the genes we possess.  As previously discussed we are made up of DNA and genes.  Our DNA acts as a blueprint, which determines what we will be, but our genes act as the parts that make up the whole.  Our genes do and will vary, which is why some people have blue eyes and others do not, and it is this variation in our genetics that leads to what nature selects for.  But how exactly does this work?  Well, it is our genes that make us or break us so to speak when it comes to survival, but as noted in the previous paragraph it’s the nature that selects, so to speak, which genes are better for survival than others.  Nature is made up of environmental and biological factors, and we will address each, starting with the environmental factors. 

Environmental factors can be broken down into physical, biological, and cultural environments.  Physical environments are made up of the inorganic, nonliving elements of the environment, such as the sunlight and rocks.  The biological environment includes all living things that exist in the environment, such as the creatures and plants.  The cultural environment is the manmade materials that exist in the environment, such as shelter, air conditioners/heaters, and clothing.  All of these factors play a role in evolution because they make up the scene that makes it either more or less beneficial to have specific genes.  For example, if an organism is lighter furred or skinned and can better blend in with its environment then it has beneficial traits, whereas any organism with nonmatching fur or skin color is disadvantaged by the environment it lives in.  The biological environment also plays a role because, as the popular saying about the zombie apocalypse goes, you need only out run or outsmart your opponent to survive.  If you cannot out compete or compete with your biological environment, specifically against predators, you won’t live very long.  Lastly, the cultural environment is also a factor because what you lack in genes you can make up with cultural innovations, which is why birds that may not be the best at getting worms can still survive if there is a bird feeder nearby. 

Biological factors also play a role, too.  When we discuss biological factors we mean one’s ability to breed.  It doesn’t do a species as a whole any good if their best, brightest, most survivable do not pass those genes on to the next generation.  See, with natural selection it is less about the individual and more about the species as a whole.  If an entire species has traits that make it survivable that’s what we, scholars, are concerned about.  If an individual has traits that are more beneficial then for the species to survive that individual must pass on his or her traits to assist the species to survive.  There have been quite a few movies based on this premise, which originated from natural selection.

So there you have it.  When we discuss natural selection we are referring to the random chance that the genes you have are what will assist you in surviving.  You have to be able to survive in your physical, biological, and cultural environment and pass those traits on to your children, or the next generation.  For those who need a review or a visual check out this awesome video (that I did not make) that provides more details on this topic.

References

Jurmain, Robert, Kilgore, Lynn, Trevathan, Wenda, Ciochon, Russell L. Introduction to Physical

Anthropology. Belmont, California: Wadsworth, 2014. Print.

The Ju'Hoansi: Africa's Surviving Foragers

Figure 1: The Ju/'hoansi

 
One of the most widely studied groups in Africa are the San, which is a broad term used to describe a group of hunter-gatherers of southern Africa.  You may have heard of them as they were also referred to as the Bushmen.  For several decades anthropologists lumped these distinctive groups together, but today we recognize that there is a need to separate out these groups and address their cultures individually.  Today’s blog post will discuss one of those groups: the Ju/’hoansi.

The Ju/’hoansi refer to themselves as the “real people” (Figure 1), and they, along with other San, are one of the extant ancestral populations from which all modern humans descended.  The Ju/’hoansi reside in Angola, Botswana, and Namibia.  While their numbers are not quite as large there were once as many as 300,000 Ju/’hoansi and San before colonial powers took over Africa. 

The Ju/’hoansi are excellent hunters and gatherers, although only 30% of their diet comes from game meat.  As the Ju/’hoansi are hunter-gatherers they exist in small, band level groups, meaning all members must contribute for the group’s survival.  Because meat is highly prized but seldom eaten the Ju/’hoansi have a unique way of deterring jealousy among men who hunt: it is customary to insult the meat.  This practice involves everyone telling the hunter that the meat he brought it tastes funny, came from an animal that was too old or two young, and/or is of generally poor quality.  These comments may not actually reflect the quality of the meat, but that’ not the point.  The point is to keep hunters humble in order to maintain the group’s survival.  Furthermore, it is actually the women (and men) who contribute to the primary source of the Ju/’hoansi’s diet: a variety of vegetative items, including Mongogo nuts and fruits (Figure 2).

Figure 2: Mongogo tree

Kinship among the Ju/’hoansi is unique.  Children are given a name from an ancestor, which cannot be used.  They must be referred to by a nickname.  Names hold a great deal of importance among the Ju/’hoansi because that dictates who you cannot marry.  Ju/’hoansi individuals cannot marry individuals with the same name as a close family member (e.g. if the father is named Robert then a woman cannot marry anyone named Robert).  Anyone who shares the name of a close family member, such as a mother or sibling, is considered a second or third individual of that family status.  This means that if your sister is named Sally any other woman named Sally would be considered your sister, as well.  This can get very confusing as there are only about 30 names available among the San, but it is not nearly as complicated as you may think when you remember that the San exist in small groups.  Furthermore, marriages are typically arranged by the parents, although divorce is allowed and is commonplace.

Unfortunately, the Ju/’hoansi have been forced to change and many are no longer nomadic.  These changes have been forced by local state governments that outlawed or limited hunting, forcing the Ju/’hoansi to become sedentary.  Several have fought back politically by purchasing land and maintaining their traditional ways of life on their private property, but modernization, big game hunting, and warfare continue to encroach on their traditional cultural ways.

 Bibliography

Peters-Golden, H.  (2011).  Culture Sketches: Case Studies in Anthropology. 6th Edition.  Mc-Graw Hill Education.