Shake-up at base of the tree of life

New research analysing huge amounts of data suggests that the comb jelly split off from sponges before other multicellular organsisms and went on to develop a nervous system independently of other animals.

Red Line comb jelly
(Image from University of California Museum of Paleontology)

You can read about it at Science Daily:

This finding challenges the traditional view of the base of the tree of life, which honored the lowly sponge as the earliest diverging animal. “This was a complete shocker,” says Dunn [no first name given]. “So shocking that we initially thought something had gone very wrong.”

But even after Dunn’s team checked and rechecked their results and added more data to their study, their results still suggested that the comb jelly, which has tissues and a nervous system, split off from other animals before the tissueless, nerveless sponge.

The presence of the relatively complex comb jelly at the base of the tree of life suggests that the first animal was probably more complex than previously believed, says Dunn.

While cautioning that additional studies should be conducted to corroborate his team’s findings, Dunn says that the comb jelly could only have achieved its apparent seniority over the simpler sponge via one of two new evolutionary scenarios:

  1. the comb jelly evolved its complexity independently of other animals, after it branched off onto its own evolutionary path; or
  2. the sponge evolved its simple form from more complex creatures — a possibility that underscores the fact that “evolution is not necessarily just a march towards increased complexity,” says Dunn. “This scenario would provide a particularly dramatic example of that principle.”

For earlier research on the origin of the nervous system, see “Nervous system originated in sponges.”

Advertisements

Rhetorical tactics: the Dembski Dodge

Wesley ElsberryWesley R. Elsberry, in discussing possible responses to factual evidence, mentioned a several avoidance tactics. This is from a long discussion thread in antievolution.org, where Wesley summarizes the patterns of common arguments. I’ve extracted them from their discussion thread and highlighted them here: how IDists avoid responding to real-world evidence.

One of the tactics is a hallmark of William Dembski’s responses about evolution, so I’ve decided to call it the Dembski Dodge.

The one I want to talk about is described below.

Non-Evidentiary Responses

The other category of approach is to ignore, so far as possible, any mention or discussion of actual fossil evidence… There are many routes to achieving this end. The simplest is non-response. The challenged person may decide that not saying anything further is the best option…. Yet another strategy is to discuss theoretical issues as if theory did away with the need to actually look at the empirical data.

funny picturesAnd there you have it. That’s the entire point of Dembski’s argument: construct a mathematical will-o-the-wisp and point at it as though it were the evidence we vainly seek.

My brother used to tease young ladies by eliciting various random facts about them, such as their eye colour, height, dog’s name, home town, favorite food, best subject, number of siblings, and so on, then multiplying the probablility of all those things being true, and producing a mathematical proof that the sweet young things in question were so improbable that they might simply disappear at any time!

And that, in a nutshell, is Dembski’s approach to the facts of biology. However, Dembski cooks the books in his favor by insisting that all the calculated events must have happened simultaneously instead of accumulating over a period of time.

Test your evolutionary knowledge at BayBlab Blog

Friday cephalopod on Pharyngula

eye of a squid, Euprymna tasmanica

Just take a look at this beautiful cepalopod eye.

It’s the eye of Euprymna tasmanica. Now, follow the link to see it full sized.

Further Thoughts linkfest

Ian Ramjohn at Further Thughts has been collecting links to the plagiarism in the Intelligent Design Creationism propaganda movie Expelled. Take a look.

Death by blogging?

This is from xkcd:

statistics on google search

A couple of bloggers have died of heart attacks. They proximate cause is probably inactivity, bad diet, lack of sleep, and perhaps stress.

Breast is best for babies with the right gene

breastfeeding a newborn Breast-feeding boosts children’s IQs by 6 to 7 points over the IQs of kids who weren’t breast-fed, but only if the breast-fed youngsters have inherited a gene variant associated with enhanced biochemical processing of mothers’ milk, reports a team led by psychologist Avshalom Caspi of King’s College London Ninety percent of youngsters possessed the critical FADS2 gene variant. It sounds like non-random natural selection to me.

%d bloggers like this: