Maybe the long-term trend across the universe is towards orthogenesis, towards greater intelligence, towards technological singularity. Just like the long-term trend for matter and energy is the formation of stars and planets, galaxies and superclusters__Ganzir, 2021
Because all living things evolved to adapt to their environments, many people deny that evolution is progressive. For example, Harvard biologist Stephen Jay Gould wrote “evolution forms a conspicuously branching bush, not a unilinear progressive sequence…earth worms and crabs are not our ancestors; they are not even ‘lower’ or less complicated than humans in any meaningful sense.”
In his book A Mirror to Nature, Science journalist Peter Knudtson writes “evolutionary theory…sees every living population of organisms on the planet as a proved evolutionary success that has by its very survival shown itself itself to be exquisitely adapted to its environment.”
He quotes anthropologist Emoke J.E. Szathmary as stating “As for superiority or inferiority–any geneticist finds this notion amusing. Each is dependent on the environmental context within which the ‘superior’ or ‘inferior’ trait (not population) evolved. Change the environment, and one may change the labelling attributed to the trait.”
Many scholars might beg to differ:
- E.O. Wilson (1975) divided life’s history into four major stages: (1) the emergence of life itself in the form of primitive prokaryotes with no nucleus. (2) the emergence of eukaryotes with nucleus and mitochondria (3) the evolution of large multicellular organisms that have complex organs like eyes and brains (4) the emergence of the human mind.
- In 1980 Arthur Jensen stated “the higher the animal ranks in the phyletic scale, the more seriously do lesions in the cortex of the brain affect its objectively measurable behavioral capacity”.
- Princeton biology professor John Bonner (1980) noted that there’s been an evolution from primitive bacteria billions of years ago to complex life forms today, and the newer animals have bigger brains than older animals and that it’s perfectly natural to say that older life forms are lower than newer life forms, because their fossils are literally found in lower strata. Even plants can be ranked he argued; angiosperm > slime molds.
- Paleontologist Dale Russel (1983, 1989) noted that the mean encephalization of mammals had tripled in the last 65 million years and that the mean encephalization of dinosaurs steadily increased for over 140 million years. Extrapolating from the latter trend, Russel argued that had dinosaurs not gone extinct 65 million years ago, they would have eventually evolved into big-brained bipeds.
- J. Phillipe Rushton (1989) argued that among modern humans, there was a Mongoloid > Caucasoid > Negroid hierarchy because Mongoloids split off from Caucasoids long after Caucasoids split off from Africans long after our species evolved in Africa.
- J. Baker et al (2015) found “an overwhelming tendency for rapid morphological change to lead to larger body size in 10 of the 11 largest mammal orders, suggesting that mammals have consistently evolved toward larger size, most likely as a response to selection pressure”
- And last but not least, pumpkin person (2017) found a positive correlations between the number of splits on the evolutionary tree a taxon was descended from, and the brain size/encephalization of said taxon.
However Gould was having none of it. In his 1996 book Full House, Gould argued that life becomes more complex over time, not because complexity is superior and thus favoured by nature, but because there’s a lower limit on how non-complex life can be, so it has nowhere to go but up. In a clever analogy, Gould compared evolution to a drunkard stumbling home from a bar. Even though each step she takes is in a random direction, she can’t get any closer to the bar because there’s a brick wall, so over time she will move further and further from the bar, not because she’s trying to get away from it, but because that’s the only direction in which her random steps can slowly accumulate over time.
Analogously, evolution started as single celled organisms and thus had nowhere to go but up in complexity. So it’s not that complexity was evolutionary favoured, but rather it was all evolution had to work with.
This explanation might explain why it look nearly 3 billion years to go from singled-cell organisms to multi-cellular life, but it can not explain why it took only half a billion years to go from multi-cell life to the most complex known object in the universe: the human brain. That’s like Gould’s drunkard taking 3 hours to stumble ten feet from the bar, and then and only an extra half hour to get from the bar to Neptune.
And how does Gould’s metaphor explain why an organ as precise as the eye “has evolved independently more than 50 times in species such as flies, flatworms, molluscs and vertebrates.”. If drunk women stumbling away from bars just happened to stumble into a location as precise as your bed on 50 different occasions, would any jury believe they all just randomly stumbled there? No they’d think you drove them there, so we should think natural selection is somehow driving the evolution of an eye because it’s a superior trait to have on pretty much any planet near a star bright enough to provide light. And once you have an eye you have sensory input, and once you have sensory input, and once you have input you need intelligence because in the succinct words of a friend’s brilliant mother, intelligence is the ability to “synthesize information usefully”.
Another example of a progressive evolutionary trend is increasing body size among mammals. Now the obvious reason why mammals would get bigger over evoultionary time is all else being equal, bigger is better. Duh. But Gould would have us believe it’s because there’s a lower limit on body size, thus there’s no where to go but up. Fortunately, Baker et al explicitly tested this theory and debunked it:
We use our PAD comparisons to test for the presence of a lower bound by drawing on ideas developed in the paleontological literature (12, 21, 23, 24) while explicitly accounting for shared ancestry. If some lower boundary on size is enforced, we expect most ancestor-descendant size changes to be positive when the ancestral size is near to that limit; it is only possible to get larger. However, as the ancestral state moves away from that limit, we predict that the distribution of body size change will become increasingly centered about 0 (i.e., size decreases are equally likely as size increases) (24). Taken over all branches of the phylogeny, this pattern predicts a negative relationship between a branch’s ancestral size and the average body size change observed along that branch (12, 21). When ancestral size is small, changes will tend to be positive, but when ancestral size is large, size can change in either direction.
We do not find the predicted negative relationship (Fig. 3D and SI Text). Instead, we find that size change actually slightly increases in magnitude when ancestral size is larger (β = 0.020, P < 0.001; Fig. 3D). This pattern is also found in the paleontological data using FAD comparisons (12). To retain the idea that some physiological lower limit could produce these PAD changes and results from paleontological data (12), proponents would have to invoke a new physiological lower limit for each new species that comes into existence. Why or according to what processes these mysterious and dynamically shifting constraints arise imposes a steep hill for this explanation to climb.