I’ve been on a recent tangent against this ridiculous notion of “more evolved” and “progressive” evolution. The two statements go hand-in-hand; mainly that if one organism is “more evolved” than another that they must have “progressed” further than a previous ancestor. But “progressing” where? A lion is adapted to African woodlands and grasslands, a penguin is adapted to life in the polar regions. Now imagine comparing two other organisms and what they need to do to pass their genes in that habitat, can you really infer if one organism is “more evolved” than another? The ultimate cause of these adaptations between these two species are migration, natural selection, mutation and genetic drift. Over time, an organism evolves traits (both phenotypic and genotypic) to better survive in that habitat. Knowing that evolution is a random process and that changes happen based on environment, can we really say that one organism is “more evolved” or “progressed” more than the organism in question? Tonight, I’ll put the final nail in the coffin for this hypothesis using Homo floresiensis as an example.
Homo floresiensis is an extinct hominid that lived on the island of Flores in Indonesia. He stood around 3 feet 6 inches tall and weight about 75 pounds, on average. Just this year, researchers from the journal Nature went to look for the oldest hominin occupation in Indonesia on an island between the Asian mainland and the island Flores, where H. floresiensis lived. Van den bergh et al found that the oldest evidence for stone tools on the island was between 118 and 194 kya, showing that there was a hominid on the island which predated H. floresiensis.
One possibility is that the older hominid was Homo erectus got to Flores around 800 kya and, over time, evolved into H. floresiensis. Though many researchers argue against this, saying that if H. floresiensis were a dwarfed erectus, then the expected brain size would have been between 500 to 600 cc (Lieberman, 2013: 124). Nevertheless, with careful examination between H. sapiens (African pygmies and Andaman islanders), Australopithecus and Paranthropus, Argue et al (2006) showed that diseases such as microcephaly are not the cause for their smaller brain, it is attributed to being a new species, Homo floresiensis. In 2009, Falk et al showed that the LB1 specimen did not have Laron syndrome, which is a rare form of dwarfism that occurs due to the body’s inability to use growth hormones (GH). The GH is secreted by the brain’s pituitary gland that promotes growth. So it was hypothesized that these diseases were the cause for their smaller stature, and in turn, smaller brains. But it seems that the cause for their smaller brains (around 400 cc) is due to the environment they evolved in, specifically a hot climate with low amounts of food.
There is amazing evidence for dwarfism and gigantism on islands. This is also shown to be effect hunter-gatherers. What is known is that H. floriensis’s skull and brain most closely resemble H. erectus, even after correcting for size (Falk et al, 2005; Baab and McNulty 2009; and Gordon, Neville and Wood 2008). (Lieberman, 2013: 123) Knowing that H. floresiensis didn’t suffer from any diseases that shrank both its body and brain, the only other explanation is that he evolved from either H. erectus, or as posited by primitive hand bones discovered on Flores, that Homo habilis, (literally handy man) somehow made it to Indonesia and swam to Flores. Either way, what we’re worried about here is how the selection for smaller body size occurred from whatever species of hominid predated floriensis, whether it be habilis or erectus.
As shown in the previous paragraph, there is evidence for island gigantism and dwarfism. So a plausible hypothesis is that either habilis or erectus swam or somehow rafted to Flores and over time due to less kcal on the island combined with the hotter climate and the dwarfism effect from the island, over time floresiensis evolved. Weston and Lister (2009) showed that island dwarfism could more than account for the depressed brain size in floresiensis. They showed that it was mechanistically possible for mammals to evolve smaller brains when compared to a mainland ancestor. This is huge. This makes the hypothesis that floresiensis is either habilis or erectus that evolved isolated on Flores.
Floresiensis shows how important energy was in human evolution. It’s thought that they survived on around 1200 kcal a day and 1400 when nursing, in comparison to erectus who survived on 1800 kcal per day and 2500 when nursing (Lieberman, 2013: 125). This is definitive proof that adequate calories are needed to drive brain growth as well as other bodily systems. Based on the energy requirements of floresiensis and erectus, it is 100 percent likely that fewer kcal was part of the reason why floresiensis evolved a smaller stature, along with island dwarfism and the climate as a whole.
The study of floresiensis and its possible precursors shows how and why the terms of “more evolved“, “progressive” evolution and “superiority” should be discontinued from evolutionary biology. Evolution acts to have an organism to be fit enough for its environment. Gauging any so-called “progressive” evolution and who’s “more evolved” than who has no basis in evolutionary biology. People who use these terms should stop saying it, as it’s been debunked. The final nail in the coffin has been put into this hypothesis. The evolution of H. florensiensis proves that selection occurs based on environment (which doesn’t even need any more proving). The final nails in the coffin have been put into the hypotheses of “more evolved“, superiority, and “progressive” evolution.
I was lucky that my high school biology teacher drove home the fact that “organisms don’t change to survive, but they survive because they changed.” That has stayed with me ever since.
It was lucky that some humans managed to find lush pastures and animals capable of domestication which provided easy food-sources and left time for contemplation of art and science. Or, maybe it wasn’t luck, but just a matter of time before some group of humans got lucky in that way?
Evolution tends to hit “ruts” or “plateaus” where no progress is made, but it seems to always evolve out of the rut when the environment invariably swings around to bestow an advantage. So, it’s not “the ability to adapt”, but the ability to be patient until adaptation is unnecessary 😉
Not necessarily. Organisms change because of natural selection. Like with peppered moths. They were white since they needed to blend into the tree bark to evade predators, however, when the industrial revolution began in Britain, the trees became dark, almost black. In a short time span, there were tons of dark peppered moths. This is natural selection working on the short term.
I think it was luck. So many things had to go “right” for us to get here today. Even if one slight thing were changed, I believe that we wouldn’t be here today.
If we replayed the tape of life from the very beginning, would we still have arose in exactly the same fashion?
Ability to adapt? Like intelligent (PP’s words)? =^)
Evolution hits ‘ruts’ or ‘plateaus’ because only so much change can occur. Natural selection can only select on the heritable traits that are currently in that population. For any new changes to occur, the environment would have to change and those less fit organisms would need to die out.