Spit-Brain Research

Evolutionary ‘theory’ is immune to satire. Satire depends on exaggeration, and evolutionary theory is such far-fetched science– substituting preposterous generalizations, non-sequiturs and jargon for meaningful scientific inference– that it can’t be satirized. It can only be described, which is funny enough.
Much of recent evolutionary self-satire involves the origin of the human brain. How did an organ of such staggering complexity and biological novelty arise? For evolutionary biologists, no speculation (except design) is too outlandish. Evidence: a paper in Nature Genetics offers a new theory to account for the human brain: spit.

According to the authors, evolution of the human brain was helped along by the evolution of spit, or more precisely, by evolution of the genes that code for the amylase enzymes in spit. Our brains needed a lot of energy, so evolution favored hominids with more effective carbohydrate-dissolving spit. The researchers noted:

That’s the big mystery of paleoanthropology…What changed [?] [sic] Why did our earliest human ancestors deviate from the pattern we see in living apes to evolve this incredibly large brain, which is very energetically expensive to maintain, and to become a much more efficient bipedal organism [?]

Solving the ‘big mystery’, the groundbreaking study

indicates that humans carry extra copies of the salivary amylase gene…humans have many more copies of this gene than any of their ape relatives, the study found, and they use the copies to flood their mouths with amylase, an enzyme that digests starch. The finding bolsters the idea that starch was a crucial addition to the diet of early humans…

Natural selection, unsurprisingly, explains it all:

…natural selection favored individuals who could make more starch-digesting protein….extra gene copies are an easy way for evolution to ramp up expression of a protein… why wait for chance mutations to improve gene function. Natural selection can favor duplicate copies of a gene that already works well, and enzyme production will increase …

Evolutionary biologists recently have reported headline-making insight into the origin of the human brain based on seven-million-year-old bone fragments , on speculation about our hominid ancestors’ preference for meat and on the genetics of fleas . Evolutionary science never rests.
The spit-brain paper no doubt contributes to the literature on salivary amylase. A study of the comparative biology of salivary enzymes- genuine science but with limited (to say the least) popular appeal- would have languished on dusty shelves were it not for the authors’ utterly unwarranted inference that their research is relevant to the origin of the human brain. It seems to be a contemporary maxim in evolutionary biology- ‘attach preposterous speculation about the origin of the human brain to your arcane research, and you’re famous’, at least for a day or two.
Nature recently published an

Michael Egnor

Senior Fellow, Center for Natural & Artificial Intelligence
Michael R. Egnor, MD, is a Professor of Neurosurgery and Pediatrics at State University of New York, Stony Brook, has served as the Director of Pediatric Neurosurgery, and award-winning brain surgeon. He was named one of New York’s best doctors by the New York Magazine in 2005. He received his medical education at Columbia University College of Physicians and Surgeons and completed his residency at Jackson Memorial Hospital. His research on hydrocephalus has been published in journals including Journal of Neurosurgery, Pediatrics, and Cerebrospinal Fluid Research. He is on the Scientific Advisory Board of the Hydrocephalus Association in the United States and has lectured extensively throughout the United States and Europe.