Research into evolution: four questions, four viewpoints

- EN - DE
Ulrich Krohs works in the Department of Philosophy and is spokesperson for the C
Ulrich Krohs works in the Department of Philosophy and is spokesperson for the Centre for Philosophy of Science. © Uni MS - Peter Leßmann

Scientists provide insights

Did Charles Darwin invent the term "evolution"

The clear answer is no. Charles Darwin didn’t invent the concept of evolution, and he himself rarely used the word. Nevertheless, the British naturalist is seen - rightly - as the creator of the theory of evolution, which explains to us the ’tribal’ development of biological species: phylogenesis.

’Evolution’ - from the Latin word ’e-volvere’ , to roll out (a scroll, for example) - has been used since the late 17th century to describe biological development. 150 years before Darwin, the term was applied to the individual development of an organism - ontogenesis. A special ontogenetic hypothesis was termed ’theory of evolution’: the entire organism was pre-formed, it was believed, in the egg cell or in the sperm, and evolution consisted only in its growth.

When Charles Darwin (1809 - 1882) presented his theory of the development of biological species through natural selection in 1858/59, the term ’evolution’ still had such a strong embryological association that he avoided it. It was only later, when other authors were increasingly using the word in a phylogenetic context, that he started using it himself.

Notions of phylogenetic evolution had already existed, and we find them in particular in the botanist and zoologist Jean-Baptiste de Lamarck (1744 - 1829). What was new with Darwin was his stating that there was an evolutionary mechanism. This explains , for the first time, the changes in species. Today, in addition to Darwin’s mechanism of variation, selection and heredity, further evolutionary mechanisms are known to us such as genetic drift - i.e. the random change in the frequency of a gene variant within a population; or niche construction - the active alteration of the environment by organisms, whereby the selection conditions are also altered for subsequent generations.

’Evolution’ is also used outside the sphere of biology, for example to describe the evolution of the cosmos or the geological evolution of the Earth’s surface. Here, the term is used more generally to describe long-term processes bringing forth new structures. And what about cultural evolution? Is this evolution in a specifically biological sense, or in a more general one? Superficial similarities with biological speciation should not make us jump to premature conclusions. The wide range of mechanisms in cultural change need to be investigated separately.

What role does evolution play in research into diseases?

An evolutionary perspective alters existing concepts of health and illness. This effect was neglected in medical research for a long time. It has only been taken into account for the last 20 years or so, as a results of the sequencing of the genomes of diverse populations in concepts of personalised medicine.

The evolutionary perspective considers health and illness against an individual’s genetic background and in the context of the respective environment. In this, evolutionary processes such as mutation, selection and drift play a particularly important role. The genomes of disparate ethnicities differ greatly, for example - both in their genetic variations and in the structure of the genome. As a result of the so-called bottleneck effect, for example - a drastic reduction in genetic variation - the genomes of European people are much less variable than the genomes of Africans, who represent the oldest population of humankind.

Starting from Africa, the human species spread out over the planet in a series of waves of migration. As a result of the evolutionary adaptations to each environment, there are clear differences between the genomes of the human populations in Africa, Asia and Europe. This genetic variation influences not only the predisposition to illness and disease but also, as a consequence, how a patient responds to medicines. This comes into effect when physicians try to make better predictions regarding an individual’s risk of illness on the basis of his or her interaction with the respective environment and by making use of clinical parameters, biomarkers and genetic information. In other words, evolutionary medicine plays an important role in research into complex (widespread) diseases.

Does evolution mean ever higher development or progress?

There are people who cannot tolerate cow’s milk. They are lactose intolerant. In fact, we owe it to evolution when we, as adults, can drink milk - and we owe it to a defect in the regulation of the lactase gene. The enzyme lactase breaks down lactose, or milk sugar. In our ancestors, this gene was deactivated after infancy because milk as food only existed in the form of mother’s milk. So why produce an enzyme in adulthood which we don’t need at all? It was not until about 10,000 years ago, when humans began to keep animals and drink their milk, that lactose tolerance evolved. A mutation ensured that the regulation of the lactase gene no longer functioned, and it spread rapidly among the human population. Is it a kind of higher development when something no longer functions as it used to? Not so! In other words, evolution can also mean simplification.

Some organisms take things to extremes: parasites often have an extremely reduced body. The parasite Sacculina, for example, consists only of a ramified network of filaments in the body of its host, a crab. Sacculina is descended from wild barnacles which include the well-known Balanidae. These have a body, with everything that goes with it. Ultimately, it is a question of adaptation to the respective environment, which can go hand in hand with increased complexity - or with reduction.

There is, finally, an interesting observation to be made when comparing the genetic material DNA. Most of the differences between individuals probably have no influence on adaptation - they are simply neutral. So in this case too we can hardly speak of progress. The conclusion is that even if the process of evolution, as a whole, represents a development towards more complexity, this is not true for every single example.

Did humans invent language, or is it a product of evolution?

The relationship between linguistics and evolutionary research focuses on the question of the origin of language. When and where, and under what conditions, did language arise? Some of the most important conditions are: walking upright, with the resultant freedom to use the hands; the lowering of the larynx; and the widening of the field of vision. The anatomy of the cranium, with the formation of the jaw and the oral cavity, as well as the volume of the brain - as demonstrated by homo sapiens today - are indispensable for the development of a spoken language. And this raises the question of language itself.

Under the influence of the neurosciences, and in the context of the philosophy of mind, Noam Chomsky - the founder of modern linguistics - defined language as "a biological property, a sub-component (above all) of the brain, an organ of the mind/brain". The old question of whether humans "invented" language, or whether language arose as the result of an "evolutionary leap" has thus become answerable: organs "grow" as the brain increases in volume. The neurologist and linguist Eric Lenneberg actually spoke of a "language-specific maturation plan", activated not only phylogenetically but also ontogenetically in the relevant development phase of the organism.

When a small child learns to speak, building up a system of phonemes, this process begins by forming the contrast between labial and dental sounds, and between nasal and non-nasal sounds - [m] and [b] or [d] and [t]. The sounds produced by the first humans are often described as grunting and clicking sounds formed at the back of the oral cavity or in the throat. What sounds Neandertals produced, and how, remains largely a matter of speculation and is a subject of controversial discussion. But their body language, gestures and facial expressions accompanied the production of sounds and served to convey information as well as to express emotions. Language really is an "organ", a natural product in a process of growth.

This article is from the university newspaper wissen