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Written by Tsirha Adefris

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Introduction

 

1.1 Humans and the natural

 1.1.1 Defining nature

 

It is Charles Darwin (Darwin|Darwin & Wallace, 1859) who brought forth the term natural into the field of science to primary consideration by regarding a natural process as a force that causes change over time among organisms: natural selection. To cite Ayala (2007), ‘Darwin's greatest contribution to science is that he completed the Copernican Revolution by drawing out for biology the notion of nature as a system of matter in motion governed by natural laws”

Nature is regarded as an entity with a self-sustaining force that constitutes those aspects of the earth that are outside human modification. In this regard the concept of the natural is opposed to that of the artificial.

Khun, T.(1962) The Structure of Scientific Revolutions

 

Figure 1: An illustration of American philosopher Thomas Kuhn’s cycle of scientific progress based on paradigms. A paradigm is a framework of knowledge in a scientific area that can change inexplicably through a revolution, such as the shift from Newton’s physics model to Einstein’s.

The basis for the study of the natural begins with studies of the origin of life. Oparin and Haldane (Gordon-Smith, n.d.) are forerunners in this study and contributed to the inquiry of the atmosphere of the early earth which was suitable to the origin of life. Although their studies have faced serious revisions, the importance of their ideas remains in linking the nonliving to the living. The natural is defined as the domain on and surrounding planet earth that is governed by various bio and geophysical cycles. The characteristics of the natural is largely attributed to the portion where observation and study have proved that nature is a system within the envelope of the ozone layer that surrounds our planet. 

The natural resides in the geological, climatic, flora and fauna, and astronomical realms. The sun provides energy to living nature by allowing photosynthesizing plants to thrive. Thus, the astronomical is not solely restricted to human space exploration, but also this important function of the sun sustaining life on planet earth.

The cell theory is an early description of the unity of living things. It is evidence that the nature of organisms is a unified entity. (Cooper, 2000) It is close to the total of earth history of 5 billion years from the appearance of the first cells to the appearance of Anatomically Modern Homo sapiens.

Humans as part of nature have bodies made up of cells. Since cells are on the entire microscopic, the human body is made up of many specialized cells with diverse functions.  Except for viruses, lacking defined cells, prokaryotes are cellular but do not have a defined nucleus. Humans belong among many other groups, to the Eukaryotes and possess a defined nucleus. 

Cell organelles serve important functions as human organs do. 

The cell nucleus contains the hereditary material. Reproduction in nature maybe asexual or sexual. That is, through simple cell division or the union of specialized cell or gametes.

The description of nature is closely tied with that of life processes in organisms. Most eukaryotic cells live according to an internal clock; that is, they proceed through a sequence of phases, called the cell cycle (Lodish, et al., 2000)

 

        1.1.2 Ecology

The science of ecology is the study of the earth’s environments from a multitude of   approaches. The concept of the natural is of primary concern in ecology. The natural emerges from the relationship of the abiotic to the biotic. The abiotic is the medium that nurtures the biotic. It is within the contentious pros and cons of the nature-nurture controversies that the defining characteristics of what is agreed upon to represent nature fall on both sides of the dispute as thus: Nature as described is the hereditary and nurture is the environmental.

Nature may also be described as the biome where the organisms of a particular habitat reside. Thus, this description places nature as equivalent to the environmental.

Ecosystems and econiches are further delineations of the natural inside the environment.

Ecology, the term deriving from the Greek word oikos for “house” is the exact perspective to examine the human environment.

The current concern of the practice is focused on restoration and conservation. (Young, 2000)

The application of ecology is equipped with various tools to measure abundance, diversity and risk of extinction for both plant and animal species. Odum, (1975) considers that ecology through its concern for species diversity and the protection of fauna and flora from human instigated interventions envisions a link between the natural and the social sciences.

Ecology is a robust branch of knowledge with multiple scientific tools that compute and estimate the nature of organisms and their relationships.

          The following ecological concepts and measures are treated in detail in chapter 4.

• Biodiversity: The diversity of life from genes to ecosystems
• Distribution: The hierarchic dispersal of organisms
• Biomass: The energy potential of select groups
• Populations of organisms: Diversity among populations
• Communities made up by interacting organisms
• Ecosystem processes such as primary production, pedogenesis, nutrient cycling and niche construction.

        1.1.3 Human Nature

          The subject of human nature occupies the enquiry of philosophers beginning with

          the ancient Greeks to the modern era.  David Hume (1739) regards the psychological

          aspects of human nature while Karl Marx (1844) is the first economist to consider

          that human nature is a historical construct within the material conditions that render  

          humans naturally tied to the productive process.

          The origins of the human species serve as a background by what is understood to be   

          human nature. The earliest documented evidence of scholarship among diverse    

          cultures all begin with a ‘creation myth’ that describes the nature of humanity.     

          Western civilization, after years of advance with the scientific method, still grapples  

          with the creation myth left behind by its Judeo-Christian forebears.

          Evidence from human development and anatomy provides evidence that humans are part

          of the vertebrate pedigree.

          Humans as all vertebrates, develop from a fertilized egg that undergoes differentiation

          into sundry cellular types until the complete individual is formed.

          The anatomical structure of humans is made up of bones and muscles that has parallels

          throughout the vertebrate clade.

          The nature of humanity is further demonstrated with the use of the subject of psychology.

          The topic of ethology and the study of instinct among classes of animals is proof that

          human thought is deep seated in nature.

          Modernity has altered the nature of humanity causing it to be examined through a

          novel lens.

          Britannica defines modernity as: the self-definition of a generation about its own  

           technological innovation, governance, and socioeconomics. To participate

           in modernity was to conceive of one's society as engaging in organizational and  

           knowledge advances that make one's immediate predecessors appear antiquated or, at  

           least, surpassed.

1.2 The Science of the Study of Humans

         1.2.1 Anthropology

The topic of study has a broad depth and diversity and only a brief    precise   is touched upon from a chosen angle in Chapter 2. Anthropology as a science came forward with a prominent concern on human diversity. This underlying interest stems from the subject’s origin as the “study of the other’s” in comparison with the intellects of the Western world.

In biological studies, genetic studies demonstrate that human variation is profuse with each individual possessing a unique signature of genes. The manner in which geographically dispersed populations interbreed also follows after this diversity. The application of the study of human variability is useful in the area of the medical sciences. Genomic medicine makes individual diagnosis based on genomic maps.

Human linguistic and cultural variations are clearly interrelated since the language of a cultural group is a mirror into its cultural norms.

Although there is evident variation in languages, the hypothesis of generative grammar appears to explain that there is a basic underlying framework for all human languages which makes interlanguage communication and transliteration possible.

There are perhaps more languages in the world among fewer cultural entities. Both cultures and languages are endangered species, especially with globalization becoming a dominant cultural force. Linguist are at work to recording languages to mitigate language loss regarded as a form of ethnocide.

Practitioners lay out the study of cultures against domains shared throughout every known cultural group. These domains such as kinship, religion, and, adaptive strategies to name a few are explained in one or another form to make the variability of cultures of surface value.

           Material culture is the result of human ideational growth. It is a historical view of the achievement     

          of humanity from the past to the present. The fundamental idea in archaeology is the relationship    

          of the human to the artistic.

         1.2.2 Applications

           Anthropology is divided into two main approaches: The academic and the applied.

Field researchers employ scientific methodology to gather and investigate evidences of the biological, cultural, linguistic, and archaeological in anthropological studies.

Such a subdivision of the study allows specialists to concentrate on areas of research which draws from the practice of focusing on the particular situation towards forming general conclusions.

Along with the genesis of generalizing principles, the subdivisions of anthropology continue to generate novel avenues along with advances in science. As an example, the study of cultures has espoused specialist areas as distinct as the studies of local music or herbal medicine.

The study of the nature of humans draws on the multi-faceted field where the researchers are identified with the physical location of the research site and their area of expertise. In so doing an entire tapestry of the nature of humans is able to be woven.

        

        1.2.3 Primatology 

        Linnaean taxonomy places humans among the order Primates. Accepted Primate species range between 350 and 190 in number. The numbers vary according to the manners and techniques    of classifications adopted. Tarsiiformes, Lemuriformes and Anthropoidea are the three suborders into which the various Primate species are distributed. Textual reference to primates outlines their features as to the following follows from a search into what describes the human.

1. Diet and dentition: Both humans and primates possess what are described as generalized dentition sharing a similar dental formula. The dental formula of the Platyrrhines is evidence for the early separation of this group from the rest. Humans are described as omnivorous, lacking a dimorphic canine and molar cusps resembling that of apes. Hunting among humans is a topic of interest in human evolution, primatologists describe the higher primates practicing this activity.
2. Brain and special senses: The human brain is large and complex, and the rest of the primates are evaluated based on comparative visual acuity rather than olfactory. Primates, as compared to the rest of the mammals exhibit the feature of a large brain.
3. Appendages: primates are described as displaying grasping hands with nails. The use of human hands in grasping object is of primary interest. The feature of human bipedality is of special interest since our species is the single primate which possesses this feature.

The locomotory mode of the higher primates is evaluated in terms of how bipedality may have arisen.

         1.2.4 Primate Ecology, Evolution and Behavior

          Primates are an arboreal species with an equatorial distribution. Primate evolutionary  

          adaptations stem from life in such a habitat. The earliest primates appeared during the

          early Cenozoic era.  Their appearance follows the extinction of the dinosaurs and the

          availability of an econiche that was evacuated as a result.

Although sociality is not unique to the order, primatologists investigate the capacity for

 sociality, tool making, and language among primates with interesting results that closely tie

 humans with the rest of the primates. The topic of Primate adaptations, evolution and

 behavior will be further discussed in Chapter 3.

Figure 2. Primate Classification and Evolution

1.3 Main Disciplines supporting Approaches to the study of Humans

         1.3.1 Evolution

Evolutionary theory is an essential perspective in the portrayal of what it means to be human. It is impossible to study human origins and diversification in the absence of evolutionary theory. Once the theory was advanced, it immediately became clear that the origins of humanity and human relationships to the rest of nature will be revised. For those who begin to ponder about human evolution at any level, there are no easy others. What appears as an easily answered question is stated as “why are there still monkeys, if humans evolved from monkeys?” If we belabor the obvious to state that humans are closely related to apes rather than monkeys, the question still stands unanswered. The answer that we should choose on Jeopardy is that monkeys or apes and humans share a common ancestor rather than monkeys mutating into humans as we watch. 

The problem with the choice answer is a problem that remains to be a point of contention among diverse practitioners with no clear candidate assigned to be a common ancestor to diverse groups of taxa even whose exact numbers are not agreed upon. 

The last common ancestor is a hypothetical denominator linking not just humans but all living organisms. It is obtained from data that produces a phylogenetic tree at suggested levels. The data itself is grainy and the outcome remains a hypothesis. 

It is in the nature of the study of man that there are no clear answers. Terms such as “probable”, “likely”, and “suggested” are dispersed throughout the literature consistently. It is no wonder that statistical treatment of diverse sorts is common. 

Practitioners never give up search for the prize find that will answer questions that still puzzle even with increasing information. The study of the human place in nature remains an exciting undertaking. 

At the very least we have convincing evidence that humans are neatly nestled inside what is commonly understood to be the natural. 

Evolutionary theory is singularly associated with Charles Darwin.  Since it has been over a century after Darwin, there are several contributions to the development and modification of the theory before and after Darwin. The science of heredity currently occupies a prominent place in evolutionary studies. The subject of evolution in the portrayal of humans is further described in chapter 4.

         1.3.2 Biochemistry

Biochemistry provides the study of the chemical foundation of life. There are five major macromolecules which comprise these. The primary of these is the DNA molecule. The genome is the hereditary information in the form of DNA that is neatly packaged inside chromosomes, uniquely typical individual as well as species wise. Far from being the “blueprint” it is professed to be it is merely a tool that allows us a means to look within species.

Research that has today resulted in sequencing previously unimagined species including fragmentary Neanderthal remains began with the evolutionary synthesis after which the theory of natural selection took a back seat to genetics.

Genetic studies always had the advantage of robust, real time laboratory research while natural selection has always been inferential.

Molecular biology is based on the association of the Mendelian theses of particulate inheritance and the identification of the genes along the chromosomes as the essence of the hereditary particles.

The study of the human genome is regarded to be an outcome of the description of the double helix. It is a tribute to James Watson that he participated in the international effort to sequence the human genome years after he produced a model of the DNA double helix with Francis Crick and Rosalind Walters.

The study of biochemistry and its applications to human evolution are further described in Chapter 5.

         1.3.3 Geology

It is generally agreed that the processes that formed our planet can be traced back to what has been termed, but not sufficiently explained: Big bang.  The Big bang is described as a process where time and energy and matter originated and exploded to form the entire Universe. Scientists think that the Earth is 4.54 billion years old. It is perhaps not coincidental that this is the same age as the rest of the planets in the Solar System, as well as the Sun. The earth apparently came into existence with the rest of the Solar System.

The estimation of the age of the earth ties in the origin of the earliest life forms. The early seas are widely believed to be where early life arose after the formation of the ozone shield. There is an alternative opinion that posits an extraterrestrial origin of life.

Uniformitarian principles are used to describe the geological features of the earth. We observe geological strata that have been laid out over the ages with the bottom layers older than the top. There are various manners of estimating the age of the earth. The most secure dates are obtained through the decay of radioactive substances.  

Organism that are embedded in rock layers may also be used to estimate time. Such bio stratigraphic relative dating methods rely on the presence of organisms of known age in the different sediments that are to be dated.

 

         1.3.4 The Fossil Record

The primate fossil record goes back to the beginning of the Cenozoic.

Paleocene fossil primates are known from North America and Europe. Due to the process of continental drift later primates are dispersed through Africa and Asia. North America and Europe lack the deposits of successive periods and we have no knowledge of the record of the evolution of the Platyrrhines, except the fact that they diverged from the rest of the primates at an early period.

The Eocene is a period where the first true primates appear also known from North America.

The record of the Oligocene provides the transition to the anthropoids where it is known from deposits in Egypt and East Africa.

The Miocene, also known as “the Age of the Apes” records ancestors of the higher apes from the record mainly dispersed in the Indian sub-continent. The Pliocene is the age where the bipedal Australopithecines are known from East and South African deposits.

The Pleistocene is a period when representative of our genus appears.

The taxonomic tribe Hominini is the designation for the assemblage of species where we belong. The Hominins as a group share adaptation for bipedal locomotion, a relatively large brain, and a reduce canine -premolar honing complex.

Our species is the only one that is in existence among the hominins. Close to 23 species among the Hominis being extinct.

It is arguable at which point in time and which evidence points to the origin of the Hominini.

Early members of the group are only known from the African continent. Molecular phylogeny pointed out that the time of divergence of the hominins from the rest of the Homininae is around 8 million BP. The earliest document Hominin, Ardipethics is dated at 4 million BP although there are other, earlier fragmentary candidates.

The Hominin genera for which we have sufficient record are Australopithecus known from East and South Africa and Homo erectus which is widespread over the entire Old World.

The study of geology and the fossil record for human evolution are further described in chapter 6.

 

 

Figure 3. The Human Fossil Record