social sciences

Evolution of language: why did humans start talking to each other?

200,000 years ago when the Homo Erectus disappeared and the Homo Sapiens was the newest species in the Hominids line, language wasn’t the same as it is today. There have been theories that development of language is linked with genetic changes. Although it is sometimes claimed that evolution takes millions of years, this usually isn’t the case. An example of short-term evolution is lactose digestion in humans of adult age in Europe. These same Europeans were likely to be lactose intolerant before they actively started to domesticate animals for milk production (Beja-Pereira, et al. 2003). Breeding for the purpose of attaining cow milk started about 8,000 years ago and in that short period of time genes linked to lactose digestion has increased in the European population.

Adaptation
Language, as it exists today,  is most likely a product of years of evolution. At least, this is what Pinker (2003) theorizes, he postulates that language is an adaptation for socially interdependent lifestyles. He points out that the use of language is a universal phenomenon across all societies. And children go through universal stages of learning a language. And in communities without a common language or deaf communities, language or sign language will spontaneously emerge (e.g. lingua franca or creole languages). He makes an interesting point that language can be used to share information with others and that expertise makes it possible for us to live in a wide range of habitats.

Social world
Dunbar (2003) discusses language being a tool to create bonds among people in larger groups. Thus language wasn’t a device to convey information about the physical world, but the social world instead. He argues that the evolution of language might have been a long process, which started off with primates making contact calls to other group members. And after this process, the environment pushed humans to adapt by being part of large social groups. In which, of course, the exchange of social information becomes of importance. Before language, the only way to connect to others is to physically groom each person individually, which is very time-consuming behavior, if done in large groups. However, with the use of language, it’s easier to talk to several others at once.
Aside from language, singing is also an important tool in large groups. The author points out that for singing language isn’t necessarily needed. The act of communal synchronized vocalizations is enough to stimulate endogenous opioids (e.g. endorphins, which creates feelings of happiness). This will make humans feel more positive toward their singing companions, and is therefore beneficial is social contact in large groups.

Archaeological evidence
Another important aspect of the emergence of language among the hominids is the ability to talk. Several organs are needed to do so, including the brain, the throat, hyoid, hypoglossal canal, and the spinal cord. And looking at behaviors and acts carried out by these hominids – hunting, creating tools, burials, migration, art – one could argue that symbols were needed to engage in these (Davidson, 2003).

Biological evidence
Up until now we are convinced that the Australopithecines had no language, so it must have emerged somewhere along the hominid line. In terms of the beginning of language, ideas exist that it didn’t start off with words, but with holophrases. It has been proposed that the emergence of syntax in language started about 90,000 years ago. Furthermore, mirror neurons have been deemed important for learning a language. Neurons are nerve cells that fire, for instance, when someone performs a behavior. However, it has been found that these same neurons also fire when we see someone perform that behavior. So this is also the case when we see someone pronounce a word. And in terms of genetics, while the FOXP2 gene was promptly dubbed the gene for language, it is not entirely clear which specific function it serves (Bickerton, 2007).

Beja-Pereira, A., Luikart, G., England, P. R., Bradley, D. G., Jann, O. C., Bertorelle, G., … & Erhardt, G. (2003). Gene-culture coevolution between cattle milk protein genes and human lactase genes. Nature genetics, 35(4), 311-313.
Bickerton, D. (2007). Language evolution: A brief guide for linguists. Lingua, 117(3), 510-526.
Davidson, I. (2003) The archaeological evidence of language origins: States of art. In Language Evolution (Christiansen, M.H. and Kirby, S., eds) Oxford University Press
Dunbar, R. (
2003) The origin and subsequent evolution of language. In Language Evolution (Christiansen, M.H. and Kirby, S., eds) Oxford University Press
Pinker, S. (2003) Language as an adaptation to the cognitive niche. In Language Evolution (Christiansen, M.H. and Kirby, S., eds) Oxford University Press
Source image.

Natural Science

The Primordial Soup Hypothesis: how did life on Earth emerge?

Long before the existence of the scientific methods we have today, mankind went looking for answers on how we came to be. Nowadays we have many different creation myths that possibly tell us the story of how everything came into existence. Several types of myths exist, for instance, in which gods create humans (e.g. Kukulkan), life emerges from nothing (e.g. Sumerian creation myths), or myths in which the world or universe starts out in a state of chaos (e.g. Pangu). But instead I will focus on abiogenesis, the course of how life can emerge from non-living particles.

Building blocks of life
A theory that fits the concept of abiogenesis is the primordial soup hypothesis. This proposition was initially put forward by Oparin and Haldane, who were inspired by experiments conducted by Miller and Urey. In their experiments they had tried to simulate a setting similar to early Earth, where organic compounds were able to form in a spontaneous manner. And this is what Oparin and Haldane postulate in terms of the emergence of life on Earth. Amino acids are often referred to as the building blocks of life, several are necessary for us to consume, as the body cannot create these by itself. At present we have identified about 500 different amino acids (Wagner & Musso, 1983). According to the primordial soup hypothesis, these amino acids formed from gases in the atmosphere and piled up in the ocean. Afterward, through chemical processes these building blocks turned into macromolecules, such as proteins. And importantly, these macromolecules were self-replicating (McNihol, 2008).

RNA, the essential macromolecule for all life
RNA, an abbreviation for ribonucleic acid, is a macromolecule that plays a big role in many biological processes in all forms of life. And the birth of RNA was an important factor in the formation of new life forms. RNA is responsible for, among other things,  carrying genetic instructions from DNA to parts of our cells that synthesize proteins. It also plays an important role in copying DNA in our bodies (Joyce, 1993).

Protocells in the primordial soup
The primordial soup refers to the primeval ocean in which the organic compounds came into existence through chemical processes.  In order for these processes to take place, sources of energy where needed. These were likely to be: radioactive decay, UV radiation, electrical discharges from the atmosphere, planetesimal impacts, and thermal energy from volcanism (Corliss, Baross, & Hoffman, 1981). These energy sources were imperative in terms of forming protocells. These first types of cells did not contain any organelles. Organelles are often described as the organs of a cell, these include structures such as ribosomes, mitochondria, nuclei, endoplasmic reticulum, etc. These structures carry out tasks that are important in a cell’s life. A theory on how modern day cells ended up with these organelles might be explained through endosymbiosis.

Endosymbiosis
Symbiosis is a common term in biology in regards to animals. A well-known example of this is clown fish and sea anemones. Both species protect each other from predators. Clown fish hang around sea anemones and scare off its natural predator, while clown fish do this to hide from their own predators. I would like to point out that this relationship isn’t necessarily intentional, the clown fish isn’t consciously protecting the anemones. This same principle can be applied to the evolution of cells. Because of organelles, such as the mitochondria taking symbiotic residency in its host cell (Kutschera & Niklas, 2005).

Beginning of life
And from here on single-cell organism life is present on Earth, this is where the evolution of life really begins. Different types of cells were formed: eukaryotic vs prokaryotic cells. Eukaryotic cells have a nucleus that carries its DNA, while prokaryotic cells do not have such a nucleus. A prokaryote is a single-cell organism, which are either classified as bacteria (e.g. E. Coli) or archaea (halophiles). Most of the other organisms have eukaryotic cells, such as humans. The earliest life forms are estimated to have emerged 3.5 billion years ago, as organic matter estimated from this time period, has been found (Allwood, Walter, & Marshall, 2006). Mondern day humans evolved from the Homo Erectus 200,000 years ago (Bradshaw, 1997). Life is still evolving and will continue to do so until the end up times.

Allwood, A. C., Walter, M. R., & Marshall, C. P. (2006). Raman spectroscopy reveals thermal palaeoenvironments of c. 3.5 billion-year-old organic matter. Vibrational Spectroscopy, 41(2), 190-197.

Bradshaw, John L. (1997). Human Evolution: A Neuropsychological Perspective. Psychology Press.

Corliss, J. B., Baross, J. A., & Hoffman, S. E. (1981). A Hypothesis Concerning the Relationships Between Submarine Hot Springs and the Origin of Life on Earth. Oceanologica Acta, Special issue.

Joyce, G. F. (1993). The RNA world: Life before DNA and protein.

Kutschera, U., & Niklas, K. J. (2005). Endosymbiosis, cell evolution, and speciation. Theory in Biosciences, 124(1), 1-24.

McNichol, J. (2008). Primordial soup, fool’s gold, and spontaneous generation. Biochemistry and Molecular Biology Education, 36(4), 255-261.

Wagner, I., & Musso, H. (1983). New naturally occurring amino acids. Angewandte Chemie International Edition in English, 22(11), 816-828.

Amino acids / protein schematic source.

Books

Why didn’t the natives come to Europe?

The history of how plants and animals spread the Earth is a fascinating one. But it is often strange to reason what caused the great differences between societies. Some people have attributed these to intelligence, which is an incorrect conclusion. Jared Diamond discusses these differences and the evolutionary process of agriculture in his book Guns, Germs & Steel. We can probably all remember from our (western) history classes that Europeans went on trips at one point, and started establishing new societies outside of their own continent.

However, why did they go on this trips? Why didn’t the natives visit Europe and create establishments there? Diamond reasons that it has to do with the environments people were in and not their innate abilities. A lot of it is dependent on the soil and other cues in the environment that made agriculture possible at one point. And Fertile Crescent is one of those places, this is an area in the Middle East. When people started domesticating plants and animals, they had more free time to invest in other projects. For instance, they could create new political systems or focus on technological innovations.

Another interesting point the author makes is the east-west major axis in Eurasia. Trade and ideas spread much easier and faster in in Eurasia, because of the limited boundaries on this axis. However, it is much different for North America, where such travel would have been more difficult.

Diamond also spends a great portion explaining how languages spread around the globe, especially focussing on Polynesia. He goes a great length to explain how and which factors contributed to the formation of agriculture and the voyages of the Europeans. And how these affected that natives living in the Americas. It is a very thorough, interesting read, definitely worth the try if you love learning more about the macro factors in history!

Societies also fall apart, leaving behind traces from which researchers try to reconstruct their story. The interesting and simultaneously scary part is that current day societies show signs that can result in their collapse, think rapid deforestation and climate change. In Collapse, Diamond explains the factors that contributed the fall of societies we mostly have heard about through history classes, such as Easter Island or Greenland. I will discuss this book in a future post.

Buy the book on Amazon or Bol.com.

social sciences

Sexual selection from an evolutionary prespective

Ask a couple why the choose each other and you probably get some story on how they thought their significant other was attractive. There are thousands of self-help books dedicated to helping you become more attractive. Even coaches exist to assist you in appearing appealing to the person of your liking. But what exactly makes people attractive? 

As suggested in the title, the following explanations are from an evolutionary perspective. This research field mainly seems to focus on heterosexual couples. Also, the first part of the theory will discuss physical attraction, the second part will look at personality characteristics. Hormones play a big role in secondary sex characteristics, which is essential in sexual selection. Men and women look at different cues that are important for reproduction.

Women
Women look for characteristics that indicate high levels of testosterone, such as a broad jaw (Grammer & Thornhill, 1994). Such characteristics are the result of evolution through sexual selection. Because these indicate important physical traits to consider such as immunocompetence (the immune system being able to fight off antigens). These are favorable hereditary traits to pass on to your offspring. Yet another indicator of good genes is facial symmetry (Scheib, Gangestad, Thornhill, 1999). Which again, could be signaling good genes, as it could indicate development stability in puberty, the body withstood pathogens and perturbations (Gangestad & Thornhill, 2003). Ovulation can also influence females’ perceptions of attractiveness. As during this phase of the menstrual cycle, females prefer more masculine faces.

Men
Men look for characteristics such as low hip-to-waist ratio since this could be an indication of good health (Sing, 1993). As for facial attractiveness, men seem to rate neonate faces as more appealing. These are faces with ‘young features’, such as big eyes or a small chin (Cunnigham, 1986). This could be due to the fact that women are fertile only for a certain period of time, which is linked to her younger years.

Personality
However, personality is still an important factor in attraction. Humor for one can influence people’s perceptions of attractiveness. Previous research has suggested that it displays intelligence. Li et al (2009) point out that someone who is already seen as somewhat appealing will be able to increase this by being funny. This means that people will also actively use this as a strategy to seem desirable to a potential partner.
People often claim ‘opposites attract’, however humans are not magnets. It actually seems like similarities attract, people are more likely to look for mates that share the same traits (Botwin, Buss, Shackelford, 1997).
Research has suggested that preferences for personality traits are influenced by culture, whereas physical attractiveness seems to be more universal. The differences between men and women were that men seemed to place more emphasis on physical attractiveness, while women looked for kindness, or humor. Though both genders found the aforementioned traits to be of importance, with intelligence being the highest ranked trait overall (Lippa, 2007).

Botwin, M. D., Buss, D. M., & Shackelford, T. K. (1997). Personality and mate preferences: Five factors in mate selection and marital satisfaction. Journal of personality, 65(1), 107-136.
Cunningham, M. R. (1986). Measuring the physical in physical attractiveness: Quasi-experiments on the sociobiology of female facial beauty. Journal of personality and social psychology, 50(5), 925.
Gangestad, S. W., & Thornhill, R. (2003). Facial masculinity and fluctuating asymmetry. Evolution and Human Behavior, 24(4), 231-241.
Grammer, K., & Thornhill, R. (1994). Human (Homo sapiens) facial attractiveness and sexual selection: the role of symmetry and averageness. Journal of comparative psychology, 108(3), 233.
Li, N. P., Griskevicius, V., Durante, K. M., Jonason, P. K., Pasisz, D. J., & Aumer, K. (2009). An evolutionary perspective on humor: sexual selection or interest indication?. Personality and Social Psychology Bulletin.
Lippa, R. A. (2007). The preferred traits of mates in a cross-national study of heterosexual and homosexual men and women: An examination of biological and cultural influences. Archives of sexual behavior, 36(2), 193-208.
Scheib, J. E., Gangestad, S. W., & Thornhill, R. (1999). Facial attractiveness, symmetry and cues of good genes. Proceedings of the Royal Society of London B: Biological Sciences, 266(1431), 1913-1917.
Singh, D. (1993). Adaptive significance of female physical attractiveness: role of waist-to-hip ratio. Journal of personality and social psychology, 65(2), 293.