Saturday, 8 June 2013

Human Evolution- Our Ancestors' Tale

We are human, the fifth ape. For it was Darwin's dangerous idea of descent with modification that has forever changed the story of our story. Since the dawn of our species, creation myths the world over have so elegantly and poetically tried to convey the narrative: the tears of the Eye of Ra was the progenitor to the first humans as the Egyptians believed, while the Indians maintained that we are the product of the mating of heaven and earth as well as the Mayans who held that our origins was the product of gold and the flesh of god. The Judaeo-Christian account of Adam and Eve in Genesis is one of many such allegories but our true ancestor's tale is much more moving. Our evolutionary past is beautiful, we should be proud of where we come from and anticipate what we may become. The story of us begins around 65 million calendar years ago, with the explosive radiation  of the arboreal Archonta, insectivorous mammals that gave rise to Chiroptera (bats), Scandentia (treeschrews) and the primates. The primates had two evolutionary advantages namely fingers and toes to grasp food and use tools as well as binocular vision; while early primates fed on insects, they developed smoothened square molars to supersede their triangular precursors to consume plants. Then 25 million years later, the family tree was bisected into the anthropoids (your monkeys, apes and humans) and prosimians (the modern tarsiers, lemurs and lorises); the New World monkeys are the direct descendants of some anthropoids that resided in South America while the ones that stayed in Africa become two additional branches: the Old World monkeys and the hominoids which bifurcated into the apes and humans. Mind you we are cousins of modern gorillas, orang-utans, gibbons and closer cousins of chimpanzees, the African apes evolved more recently and we evolved may anatomical differences. Bipedalism or walking upright on two legs is an evolutionary hallmark we take for granted, our foramen magnum shifted under the skull while the nuchal region became smaller. Our ribcage developed an barrel morphology (a contrast to the inverted funnel shape of other apes), the vertebral column gained a forward curvature, the pelvis broadened and a shorter distance between the hip joint and the sacroiliac emerged. The hallux or big toe lost its ability to oppose while our thumbs are opposed enabling us to grasp and the brain's lunate sulcus shifted backwards. It's tempting to think of the lineage to modern homo sapiens as very linear but the 'march of progress' theme isn't really a true account; human evolution entailed several parallel lineages and it's a challenge for palaeontologists to discern ancestral branches from dead-ends. Next we see the emergence of the australopithecines in Africa about 3 million years ago, specimens such as A. Africanus, A. Afarensis and A. Robustus were relatively small but heavy boned. Then Homo habilis, found by the Leakeys and then Homo erectus (continually we see the development of a bigger and bigger brain) as seen in the Java and Peking man specimens; the Neanderthals were displaced by the emergence of the Cro-Magnons and human races differentiated soon after. There is a problem however with the classification of human races, when you compare characters like blood type, genetic variation fails to correspond or even correlate to visually perceived skin colour. Moreover, such a genetic diversity would demand a ridiculously high rate of mutation to be accounted for by an initial single human couple, we don't see an 'Adam and Eve' in any bottlenecks of reduced populations: there was simply no first person.


  1. Hello, I'm the friend that got your blog from the debate. The one where you passionately rose up to fight against censorship :P

    Can i get your email address or number as a direct way of communication? Simply email me back at

    Also in relation to this article, i would like to ask whether you truly believe that randomly occuring mutation through radiation from the sun was sufficient enough in allowing for the immense complexity and difference in between species

    1. Hey, nice to catch up again. Thanks for visiting my digitial abode. As per your question, it's important to recognise that the origin of life and the diversity of species are two separate questions. The origin of life is unknown, with many competing yet plausible hypotheses.

      As for the diversity of life, that is where evolution comes in. I accept evolution based on the evidence of reality. Also it's critical not to assume that it is inherently 'random'. Mutations may be probabilistic (random) in nature, but evolutionary mechanisms such as natural selection are non-random and based on the differential spread of genes.

      A good analogy is a game of poker. In poker you get a random hand of cards, but eventually you are going to get four aces (the hand is naturally selected) and you will win some money. Natural selection is the non-random filtering mechanism. And this is quite sufficient to explain the diversity of species via speciation, genetic drift and selective pressure.