Mice and Elephants

A Cretan Dwarf Elephant skeletonFor March 16 on the DpSU front we had Mouse to Elephant Needs How Much Evolution? This, as I already alluded to, (incorrectly) accuses the authors of a study of circular reasoning.

How come? Well, in his own words:

How much time would evolution need in order to make a mouse the size of an elephant?

Since this kind of evolution supposedly occurs too slowly for biologists to observe, one place to look for answers is in the fossil record. But in order to answer this particular research question, a team of evolutionary biologists made some large assumptions.

The group published what amounts to a circularly-reasoned argument in a peer-reviewed journal. They estimated the maximum rate of evolution to achieve the most extreme change in mammal sizes. To do this, however, they had to first assume that small changes in size that are observed today had no limits in the past. In other words, they assumed that a mouse could turn into an elephant given enough time.


The paper was The maximum rate of mammal evolution in PNAS, from way back in January. They were studying a lot more than mice and elephants: their findings included the discovery that whales can increase their size much faster than terrestrial mammals, and that dwarfism – such as in the case of the Cretan elephant above – can occur an order of magnitude faster than size increases. But Mr Thomas isn’t concerned with all that:

The study authors wrote, “Achieving such a large transformation calls for major biological reorganization,” a task that they assumed was no problem for nature. But in real life, reorganization never occurs by accident, and it always results from personal intent.

I never intend to reorganise the contents of my bookshelf onto the floor – it just happens. Sand and pebbles will reorganise themselves in braided rivers to form new islands and demolish old ones. In short, Mr Thomas is plainly mistaken.

But back to this circular reasoning claim: what were they actually doing?

And how did the biologists calculate the evolutionary time required for their formulae? In supplementary information provided in their Proceedings of the National Academy of Sciences paper, they wrote, “The number of generations or biological time tg experienced by a lineage or population is equal to the chronological time t experienced divided by generation time: tg = t / G.”

What about it? More important is how they calculated the magnitude of the change, but Mr Thomas isn’t going to tell us that now, is he?

So, they calculated the number of generations by dividing chronological (historical) time by the time between generations. And from where did they obtain this chronological time? From the evolutionary age assignments attached to fossils! Their report referred to mammals known from fossils “70 million years ago.”

Heresy!

According to a Monash University press release reporting on these findings, “scientists have for the first time measured how fast large-scale evolution can occur in mammals, showing it takes 24 million generations for a mouse-sized animal to evolve to the size of an elephant.”

Here’s the press release: Mouse to elephant? Just wait 24 million generations.

But of course they would say a mouse requires 24 million generations to turn into an elephant, since that’s how many generations fit into the supposed millions of years between smaller mammals found in lower strata and larger mammals in higher strata. But if the distribution of mammals in various strata resulted from the waters of Noah’s Flood inundating successive niches, then the age assignments are wrong, along with studies that assume them.

So, scientists did not directly “measure” evolution. How could they, without a time machine? Instead, they used circular reasoning by assuming that evolution can overcome any biomechanical obstacle, and by assuming the very timescales that they “measured.”

This is not circular reasoning. It is the equivalent of calculating the displacement and dividing by the time elapsed to find the velocity – there is no circular reasoning there, and nor is there in this paper (at least so far as I know, and Mr Thomas certainly hasn’t demonstrated it).

Admittedly, the simple statement that it takes 24 million generations to change from mouse-sized to elephant-sized doesn’t tell us much. That is the equivalent of the time and displacement, what we want is the rate, and of multiple species so a comparison can be made. And this is what the study did: so what if the headline went with this little tidbit?

As you know, normally in these DpSUs Mr Thomas takes a story and tries to bend it to his creationist point of view. In this case he cannot, and has to attack it. Vague allegations of “circular reasoning” seem to be his last resort – he’s done it before in a similar way. And if that’s all he can come up with I would be pretty confident with the findings of this study. Though then again this is the man who mucked up attacking the gyres guy…

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3 thoughts on “Mice and Elephants

  1. I love the way they get indignant over the results matching up with predictions.

    It should take ~24 million generations! Wait…it does? THEREFORE CREATIONISM!

    • And that’s really why I think he scraped the bottom of the barrel here – the whole article can be construed as an attempt to persuade the faithful that they have a counter without ever actually providing it.

    • The main thrust of their argument always seems to be very similar.

      “This is an article about evolution that it includes evolution! That is an assumption because the article wasn’t prefaced with Dawkin’s “Greatest show on earth” or some other evidence for it. They just investigated evolution as though it were a commonly accepted scientific fact! The nerve!”

      It’s bloody bizarre.

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