Home » Evolution » Dinosaurs, Brains, and ‘Progressive’ Evolution: Part II

Dinosaurs, Brains, and ‘Progressive’ Evolution: Part II

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JP Rushton

Richard Lynn

L:inda Gottfredson


1700 words

In part I, I showed how Dale Russel’s contention that the troodon would have evolved into a bipedal ‘dinosauroid’ with human locomotion and a human-sized brain was pure fantasy. I ordered the book of his that Rushton cited in his book Race, Evolution, and Behavior and I finally received it last week. When I read the relevant parts, I yawned because it’s the same old stuff that I’ve covered here on this blog numerous times. Since literally the only relevant part in the book about the troodon is the final 7 pages, that’s what I will cover today—along with a few more lines of evidence that large brains lie outside reptilian design (Gould, 1989).

First off, all of Rushton’s contentions in the final pages of his book (Rushton, 1997) need to be rebutted. Rushton (1997: 294) writes that dinosaur brains were ‘progressing’ in size for 140 million years, but neither of Russel’s writings that I have (Russel 1983; 1989) have the statement in them.

In the book Up From Dragons: The Evolution of Human Intelligence neuroscientist, evolutionary psychologist John Skoyles and science writer Dorian Sagan—the son of Carl Sagan—speak briefly about reptilian intelligence and why they wouldn’t have reached our levels of intellect:

But cold-bloodedness is a dead-end for the great story of this book—the evolution of intelligence. Certainly reptiles could evolve huge sizes, as they did over vast sweeps of Earth as dinosaurs. But they never could have evolved our quick-witted and smart brains. Being tied to the sun restricts their behavior: Instead of being free and active, searching and understanding the world, they spend too much time avoiding getting too hot or too cold. (Skoyles and Sagan, 2002: 12)

Hopson (1977: 443) writes:

I would argue, as does Feduccia (44), that the mammalian/avian levels of activity claimed by Bakker for dinosaurs should be correlated with a great increase in motor and sensory control and this should be reflected in increased brain size. Such an increase is not indicated by most dinosaur endocasts.

Most importantly, if some dinosaurs DID have bird-sized brains, the above contention would still hold. Hopson concludes that, except for coelurosaurs “the range of behaviors that existed in dinosaurs, as inferred from trackways and skeletal morphology, may not have lain much outside the observed range in ectothermic crocodilians” (Hopson, 1977: 444).

Since the conjecture/’thought experiment’ of the troodon was rebutted last week, it’s pretty conclusive that large brains lie outside of reptilian design; they need to spend so much time avoiding getting too hot or cold—as well as hunt and eat—so exploring the world and learning was not possible for them—along with the fact that they didn’t have a primate morphology and thus didn’t have the ability to fully manipulate their environment as we do which would further select for larger brains. However, as Hopson (1977) notes, animals with higher metabolic rates had larger brains; coelurosaurs had high metabolic rates and the largest dinosaur brains (Russel, 1983; 1989)—but that doesn’t mean they would have eventually evolved human-like intelligence, bipedalism or brain size and to say otherwise is fantasy.

Furthermore, there is large variation in encephalization and encephalization is not universal in mammals (Shultz and Dunbar, 2010).

Here is the thing about brain size increases: it is a local level trend. A local level trend is a trend that occurs within one or a few related species. This is exactly what characterized brain evolution; there is large variation depending on what the environment calls for (Boddy et al, 2012; Montgomery et al, 2012; see also island gigantism; Bromham and Cardillo, 2007; Welch, 2009; and also see the deep sea rule; Mcclain, Boyer, and Rosenberg, 2006). So these local trends differ by species—even one population split by, say, 50 miles of water will speciate and become evolve a completely different phenotype due to the environment of time. That is evolution by natural selection; local change, not any inherent or intrinsic ‘progress’ (Gould, 1996).

The same local level trend occurs with parasites. Now think about parasites. The get selected for ‘complexity’ or a decrease in ‘complexity’ depending on what occurs in their host. Now, looking at it from this perspective, the body is the host’s environment while the earth is ours; so my example for an environmental change would be, as usual, the asteroid impact hitting the earth blocking out the sun and decreasing high-quality food all throughout the earth. Surely I don’t need to tell you what would occur…

Russel (1989) writes:

Examples of evolutionary changes that occured at ever-increasing speeds include the initial diversification of animals in the sea 650 and 550 million years ago, the attainment of tree stature in land plants between 410 and 360 million years ago, and the diversification of mammals between 200 million years ago and the present. Changes like this have resulted in increased organismal complexity, which, in combination with a general increase in number of species, has made the biosphere of the modern Earth so much richer than it was several hundred million years ago. It is reasonable to suppose that animals living in a complex environment might find it advantageous to possess complex nervous systems in order to have access to a greater variety of responses. Indeed, the largest proportion of brain weight in an animal has also increased at an ever-increasing rate across geological time. The brain has become evidently larger in animals as diverse as insects, mollusks, and backboned creatures. Relative brain size can be taken as an indication of biotic interactions.

He references time periods that correspond with decimations (mass extinctions). Decimations lead to diversification. Think back to the Cambrian Explosion. During the Cambrian Explosion, many more lifeforms existed than can be currently classified. Therefore, according to the decimation and diversification model, greater diversity of life existed in the past. When decimations (defined as a reduction in the anatomical forms of life from mass extinction) occur, the niches that become extinct quickly become filled.

The time periods that Russel references are when mass extinctions occurred. This is how diversification occurs. What allowed for this ‘organismal complexity’ and increase in the number of species (though body plans are limited due to the Burgess Decimation) is due to the decimations. Decimation and diversification proves that evolution is not progressive.

A ‘trend’ in biology is directional change in a group stat using the mean, median or mode. Any existence of a trend from the mean (‘progress’) tells us nothing about the underlying mechanisms behind it.

To wrap this all up, even if a trend in X were to be discovered, it still wouldn’t tell us a thing about the underlying mechanisms causing it, nor will it tell us about any increasing tendency. 

The analogy of the drunkard’s walk (Gould, 1996) is why ‘progress’ doesn’t make sense. Further, niche construction matters as well. When organisms construct their own niches, change occurs based on those niche constructions. Milk-drinking 8kya in Europe and African farmers diverting water for their crops having mosquitoes come by and gaining a resistance to malaria are two examples of niche construction (Laland et al, 2009). That’s another barrier to progress!

In sum, Dale Russel says nothing I’ve not heard before in regards to ‘progressive’ evolution. He only describes ever-increasing ‘complexity’ which is due to decimations and further diversification by organisms to fill empty niches. Any type of ‘progress’ would have been stymied by mass extinctions.

Further, the fact that species can consciously—in a way—guide their own evolution through the manipulation of the environment once again shows how evolution doesn’t mean progress—it literally only means local change and any type of local change, no matter to what type of environment, will cause concurrent increases/decreases on whichever relevant traits that will give the organism the best chance for survival in that environment.

This is why evolution is not progressive; and even if scientists were to identify one thing, still, a causal mechanism won’t be able to be inferred. Ruseel (1989) describes right and left walls of complexity—nothing more. Dinosaurs didn’t have the body plans to have our brain size, bipedalism and intelligence, nor did they have the right type of blood, nor did they have the time to search and learn about the world due to being constrained to their cold-blooded system—being a slave to the sun, always attempting to avoid overheating or getting too cold (Skoyles and Sagan, 2002). The so-called ‘dinosauroid’ is an impossibility and implies a teleological lean to evolution—as if our morphology (or something similar from an unrelated organism) will always evolve if we replay the tape of life again (Gould, 1989; 1996). This is what Russel is pretty much arguing, and he is 100 percent wrong as noted above.


Bromham, L., & Cardillo, M. (2007). Primates follow the ‘island rule’: implications for interpreting Homo floresiensis. Biology Letters,3(4), 398-400. doi:10.1098/rsbl.2007.0113

Boddy, A. M., Mcgowen, M. R., Sherwood, C. C., Grossman, L. I., Goodman, M., & Wildman, D. E. (2012). Comparative analysis of encephalization in mammals reveals relaxed constraints on anthropoid primate and cetacean brain scaling. Journal of Evolutionary Biology,25(5), 981-994. doi:10.1111/j.1420-9101.2012.02491.x

Gould, S. J. (1989). Wonderful life: the Burgess Shale and the nature of history. New York: Norton.

Gould, S. J. (1996). Full House: The Spread of Excellence from Plato to Darwin. New York: Harmony Books.

Hopson, J. A. (1977). Relative Brain Size and Behavior in Archosaurian Reptiles. Annual Review of Ecology and Systematics,8(1), 429-448. doi:10.1146/

Laland, K. N., Odling-Smee, J., Feldman, M. W., & Kendal, J. (2009). Conceptual Barriers to Progress Within Evolutionary Biology. Foundations of Science, 14(3), 195–216.

Mcclain, C. R., Boyer, A. G., & Rosenberg, G. (2006). The island rule and the evolution of body size in the deep sea. Journal of Biogeography,33(9), 1578-1584. doi:10.1111/j.1365-2699.2006.01545.x

Montgomery, S. H., Capellini, I., Barton, R. A., & Mundy, N. I. (2010). Reconstructing the ups and downs of primate brain evolution: implications for adaptive hypotheses and Homo floresiensis. BMC Biology,8(1), 9. doi:10.1186/1741-7007-8-9

Russell, D. A. (1983). Exponential evolution: Implications for intelligent extraterrestrial life. Advances in Space Research,3(9), 95-103. doi:10.1016/0273-1177(83)90045-5

Russell, D. A. (1989). An Odyssey in Time: The Dinosaurs of North America. Minocqua, WI: Published by NorthWord Press in association with National Museum of Natural Sciences.

Rushton J P (1997). Race, Evolution, and Behavior. A Life History Perspective (Transaction, New Brunswick, London).

Shultz, S., & Dunbar, R. (2010). Encephalization is not a universal macroevolutionary phenomenon in mammals but is associated with sociality. Proceedings of the National Academy of Sciences,107(50), 21582-21586. doi:10.1073/pnas.1005246107

Skoyles, J. R., & Sagan, D. (2002). Up From Dragons: The Evolution of Human Intelligence. New York: McGraw-Hill.

Welch, J. J. (2009). Testing the island rule: primates as a case study. Proceedings of the Royal Society B: Biological Sciences,276(1657), 675-682. doi:10.1098/rspb.2008.1180



  1. I do not think that the biology of cold-bloodedness has anything to do with dinosaurs not evolving into humanoid bipeds. Any biological feature can change as long as selection pressures force change. Mammals we cold blooded once yet now they are not. The real reason dinosaurs would not become humanoid is in how they take care of their young. Apes hold their babies dinosaurs did not. Monkeys are social because of touch. Raptors are like wolves and carry young in the mouth. If they did care for young like apes then yes they would become humanoid. But there are many reasons they did not. Once is that babies are vulnerable and it takes intelligence not to let them die if you are an ape. Raptors lay eggs that by instinct know survival and do not need education. Primates teach and hold babies a long time. Humans hold their babies the longest. Raptors would never evolve to hold babies thus never gain that type of social intelligence. Their hands would not develop like human hands. Raptors would be more like kangaroos. Kangaroos are bipeds yet unlike humans have weak hands. Holding babies develop your hands and social skills. Roos don’t need complex hands to be bipeds. And why would a Raptor even need thumbs? Don’t see how that would develop if not used to carry babies and look in their eyes.


    • Phil78 says:

      “I do not think that the biology of cold-bloodedness has anything to do with dinosaurs not evolving into humanoid bipeds. Any biological feature can change as long as selection pressures force change. Mammals we cold blooded once yet now they are not.”

      Technically Mammalian ancestors who transitioned from reptiles were synapsids, who in turn were warm blooded.

      Technically true “mammals” were never cold blooded. But your point still stands, as it was unlikely that dinosaurs were actually cold blooded, at least strictly, based on recent research.

      Your point of “childcare” basically aligns with his point of primate morphology.


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