The Problem With Evolutionary Explanations
A new theory attempts to explain why mammals vary from teaspoon size to battleship size. But what does it really explain, if anything?
There are two aspects to scientific investigation: fact-gathering (the “what”) and explanation (the “why”). Much of day-to-day science is the former: carefully cataloguing phenomena in the natural world, whether they be stars, wildflowers, proteins, or anything else observable. But this is often considered mere stamp collecting without a theory to explain how things got the way they are.
Science Daily advertised, “From Tiny to Massive, Mammal Size Evolution Explained.”
Scientists have added another piece to the evolutionary puzzle to explain why certain mammal families evolved to be very large, while others remained tiny. In research published in Proceedings of the Royal Society B, an international group of scientists including Monash University’s Dr Alistair Evans proposed a new theory explaining the diversity of mammal sizes — from the Etruscan shrew which weighs around two grams, to the blue whale which clocks in at almost 200 tonnes.
A look into the article, however, shows much “what” with very little “why.” Evolutionary theory’s duty here is to explain the patterns, not just catalog them. Moreover, evolution needs to make testable predictions and falsify alternative explanations. Evolution should also tie the observations to its core concept, fitness by natural selection, in such a way that Darwinian evolution stands as the best explanation out of all contenders.
The first part of Dr. Evans’ proposal is that “baby weight relative to adult body mass is key.” But where is the explanation in his focus on size?
“Size is fundamental to your life and your body — how fast your heart beats, how much food you need to eat, and how you move,” Dr Evans said.
Classification of mammals (the “stamp collecting”) has already shown what people have known for millennia: size differences are plentiful and obvious. The meat of the new proposal seems to be in a relationship between speed of maturation and maximum body size:
Following the extinction of the dinosaurs, mammals flourished and their size increased dramatically. The study examined the maximum size of groups including whales, elephants, primates and rodents over this period to examine the constraints on size.
The researchers found that species that matured more quickly and produced a larger mass of young each year relative to body weight were able to evolve to a larger maximum size. Further, they are likely to reach that size in fewer generations.
This high rate of biological production is vital, regardless of whether many small young or just one large offspring are born in a year.
Finding a relationship, though is a “what,” not a “why.” For instance, when Henrietta Leavitt discovered a period-luminosity relationship in variable stars, it proved a useful pattern, but it did not explain why stars vary. Can evolution explain why some mammals develop faster and others don’t?
Dr Evans said whales were an excellent example of the theory.
“The blue whale is the largest animal to have evolved, even larger than dinosaurs, and it reached this size at the fastest rates we recorded. Key to this success is that they produce large young that mature quickly, reaching around 30 metres in eight to 10 years,” Dr Evans said.
Lead author of the study, Dr Jordan Okie from Arizona State University, said primates were at the opposite end of the spectrum.
“Primates have a low production rate and have evolved very slowly. They have never got bigger than about 500 kilograms,” Dr Okie said.
Again, though, these are “what” statements, not “why” statements. None of these statements relate to fitness by natural selection. Presumably, both apes and whales are fit, else they would not have survived to the present day.
Dr. Evans added a “really surprising finding” from his team’s study. Is it more than just another pattern — a why instead of a what?
The study also linked maximum size to mortality rate. Because larger animals tend to breed less frequently than smaller animals, if the mortality rate doubles, the maximum size is predicted to be 16 times smaller.
A supporter of the theory might say that a prediction was just made. Measure the breeding rate, factor in the mortality rate, and you can predict the maximum size of an unknown mammal. Evans applied his theory to explain extinctions after the Ice Age, on the basis that “changing climates probably increase mortality rates.” If so, then climate changes today might exacerbate extinctions, because “it takes a long time for their population to rebound from disasters.” A supporter might also point out that such information is useful to scientists and politicians who must consider the ecological effects of human activity.
Whether any of this amounts to scientific explanation based on evolutionary theory will be considered in the comments.
Assignment: Analyze the proposal to see whether Darwinian theory came through on its promise to explain the diversity of mammal sizes and the patterns observed. Remember, it’s not enough to say that patterns or relationships exist. Evolutionary theory needs to explain why they exist. Try your skill, then come back later in the day for our commentary.
—– 18 hour break —–
How did you do? Oh, for a modern Socrates to roam the halls of academia to embarrass evolutionists like these into realizing they have no idea what they are talking about.
Experienced Baloney Detectors surely noticed right off that the proposal did not apply evolutionary theory; it merely assumed it. It’s another case of shutting down understanding by saying, “It evolved” (see cartoon).
Here’s Evans’ theory in a nutshell: small animals evolved to be small because they were able to evolve to be small, and large animals evolved to be large because they were able to evolve to be large. Satisfied?
If you don’t believe it, look at that quote above: “The researchers found that species that matured more quickly and produced a larger mass of young each year relative to body weight were able to evolve to a larger maximum size.” What, pray tell, was added to knowledge of current mammals who mature quickly and produce a larger mass of young to explain why they have those lifestyle patterns? Stating that they were able to evolve that way is a circular argument. It’s completely vacuous. And why did the small animals stay small, if fitness was better on the large-size peak? Oh, we get it; they were able to evolve to be small.
This is how evolutionists are able to pretend to be scientists with jargon and hand-waving. No understanding was added by evolutionary theory. None. Everyone already knew that mammals show tremendous diversity in maximum size, clutch size, maturation rate, and every other observational fact mentioned in the article. Aristotle knew these things. Creationists and intelligent design advocates know these things, and use design arguments to explain them. So here comes Darwin, selling the notion that “It evolved because it evolved,” expecting us to say Wow, he’s the man.
If Darwiniacs want us to buy their snake oil, they have to show it cures misunderstanding and produces enlightenment. It’s not very enlightened to run around in circles drinking Darwine.