Pelagic Larval Stage

September 3, 2011

I love this video of baby giant octopi (5mm long) at the Vancouver Aquarium:

The CBC has an article about the event  and states that it is unlikely that any of the 300 hatchlings will survive:

Chances of survival are very low because giant Pacific octopuses have a seven to ten month long pelagic larval stage. To further our knowledge of octopus reproduction, we will attempt to feed and maintain some the larvae for as long as possible.

Pelagic means open water, think deep blue (i.e. no bottom) vs. a reef. I first read about pelagic larval stages in the book Reef Fish Behavior and was blown away at how profoundly different this mechanism is compared to anything I’m used to in the animal world.

I have a built-in assumption that parents and offspring share the same habitat (think Finding Nemo). With most reef fish, not only do the babies never see their parents again, they most likely will never see the same reef their parents inhabit. There is no nepotism on the reef.

How cool is that? And the giant Pacific octopus larvae can’t survive without this stage, or at least no one has figured out what is missing in an aquarium environment (yet).

Disgusting Ultimatums

March 2, 2009

CBC radio’s Quirks and Quarks show had a segment on the disgust response. One of the experiments demonstrates that people playing the ultimatum game show the facial disgust response when they receive a low offer that they ultimately reject. From a press release:

“Morality is often pointed to as the pinnacle of human evolution and development,” says lead author Hanah Chapman, a graduate student in the Department of Psychology.  “However, disgust is an ancient and rather primitive emotion which played a key evolutionary role in survival.  Our research shows the involvement of disgust in morality, suggesting that moral judgment may depend as much on simple emotional processes as on complex thought.” The research is being published in Science on February 27, 2009. 

This is why I found the research on chimps playing the ultimatum game with raisins so fascinating. Chimps play the way rational economists play (they accept any amount) while humans reject unfair offers on moral grounds. 

This adds to the work of Dan Kelly who believes the human moral system has co-opted the disgust system.

CBC’s “The Nature of Things” premiered a documentary called The Hobbit Enigma last night. I’ve covered this topic briefly in a series of posts I called Pygmy vs. Hobbit. The documentary was awesome…. at least for an off-by-one nerd like me. 

“The Hobbit” is a set of hominid remains found on the Indonesian island of Flores. These remains have been dated to be 18,000 years old which means they were contemporary with modern humans. 

The question is whether this is a completely new species (Homo floresiensis) or a subspecies/variant of an existing known hominid including possibly ourselves. You can find more details about the Homo florensiensis debate on Wikipedia. 

The evidence demonstrating that the small size was not due to microcephaly was interesting, however, ruling out a single pathology does not rule out ALL pathologies. The most pursuasive evidence supporting a new species was the demonstration that the carpal bone system matches early hominids or chimps.

The documentary also suggested that The Hobbit may be Australopithecus, that is, the same species as Lucy

The implications of this debate are far reaching. It is not simply a matter of adding a new species to the Hominid family tree, but one that challenges the “out of Africa” assumption. The head scratcher is how this species got to Flores. We know Homo erectus (much earlier) and us (Homo sapien sapien) were in this area, so The Hobbit being subspecies/variant of one of these two species does not challenge any long standing assumptions. If The Hobbit is Australopithecus or something completely new it is means we have to go back to the evolutionary drawing board.

Well well. I might be smarter than I look.

This is another post about the long running Hobbit vs. Pygmy debate. The debate is about the hominid skeletal remains found on the Indonesian island of Flores in 2003. Some say it is a Hobbit (new species Homo floresiensis) and others say it is a Pygmy Homo sapien. In my original post I put my money on the species being a Pygmy H. Sapien (a very small version of our species).

In my next post I backtracked after new evidence seemed to be pointing at a Pygmy H. erectus.

Well, a new theory claims that the Hobbit is H. sapien suffering from severe iodine deficiency.

…comparisons of the fossils with modern bones suggested that they were actually human, with their small stature and distinctive features the result of a condition related to severe iodine deficiency.

According to this theory, the Flores Hobbit is a human suffering from cretinism. Score another one for Occam’s razor (for now).

Garbage Bags and Spandrels

February 19, 2008

I love outdoor black garbage bags with the quick tie feature. Instead of a straight cut, the top of the garbage bag is cut in a curved shape so that you end up with two longer edges that are easy to grab.

Now I’m sure that quick tie was a wonderful feature on its own. Many garbage bag executives probably struggled with the idea of re-engineering their manufacturing processes to add this functionality. For me, I couldn’t care less about the extra handle-like feature. So why do I love them?

Well, having the curved cut has a positive side-effect. A spandrel in evolutionary biology terms.  The curved cut allows me to easily tell the “open” edge from the sealed edge. No more pulling back and forth between the two edges unsure of which side is supposed to open.

Now I’m sure there are other ways to distinguish edge that opens from the sealed edge but it makes me happy that this minor irritation was fixed inadvertently by a feature designed with a whole different purpose in mind.

RADBags with New Opening Detection Technology.  What a wonderful discovery :-)

Two new pieces of evidence were announced this week that should shed some light on hominid evolution. First, researchers at Arizona State University have shown that anatomically modern humans exhibited advanced behaviors earlier than expected.

“Our findings show that at 164,000 years ago in coastal South Africa humans expanded their diet to include shellfish and other marine resources, perhaps as a response to harsh environmental conditions,” notes Marean, a professor in ASU’s School of Human Evolution and Social Change. “This is the earliest dated observation of this behavior.”

Further, the researchers report that co-occurring with this diet expansion is a very early use of pigment, likely for symbolic behavior, as well as the use of bladelet stone tool technology, previously dating to 70,000 years ago.

There is a boundary between “anatomically modern humans” (Homo sapiens) and the modern humans that left Africa approximately 50,000 years ago (Homo sapiens sapiens). The question is whether there was a true speciation event at this boundary or whether there was simply a kind of cultural renaissance.

Those that support the idea of a speciation event believe that a change in the brain accounts for the difference and that the most likely brain change involved language.

The second major piece of evidence may rule out the language theory. The analysis of Neanderthal DNA has shown that Neanderthals possessed the same FOXP2 gene as modern humans (i.e. us).

Neanderthals, an archaic human species that dominated Europe until the arrival of modern humans some 45,000 years ago, possessed a critical gene known to underlie speech, according to DNA evidence retrieved from two individuals excavated from El Sidron, a cave in northern Spain.

The new evidence stems from analysis of a gene called FOXP2 which is associated with language. The human version of the gene differs at two critical points from the chimpanzee version, suggesting that these two changes have something to do with the fact that people can speak and chimps cannot.

So that really throws a wrench in things. If the modern FOXP2 gene is an accurate test for advanced language then everyone and their sister with an over-sized brow had language. Perhaps another change independent of language occurred that can account for the explosion of advanced behavior in Homo sapien sapien 50,000 years ago or maybe we should send the “sapiens sapiens” name back to the department of redundancy department.

Primate researchers at the Max Planck Institute report fascinating results for a chimpanzee friendly version of the ultimatum game.

In each version of this mini-ultimatum game, the proposer could pull one tray with 8 raisins for himself and 2 for the other (an unfair split that people routinely reject). However, the proposer would have a choice. In one game, he could choose between this unfair offer and a fair one (5 raisins each). In another, he could choose a hyper-fair option (2 for himself and 8 for the responder). In a third, he had no choice (the second tray also had 8 for himself and 2 for the other). In the fourth game, the proposer’s other choice was hyper-unfair (10 for himself, 0 for the responder).

Unlike humans faced with these games, chimpanzee responders accepted any nonzero offer, whether it was unfair or not. The only offer that was reliably rejected was the 10/0 option (responder gets nothing). The researchers conclude that chimpanzees do not show a willingness to make fair offers and reject unfair ones. In this way, they behave like selfish economists rather than as social reciprocators.

Assuming that the experiment accurately mimics the human ultimatum game, this is a major finding (in my mind anyway). Humans tend to punish the proposer for deviating from an equal split while chimps will take any non-zero amount. How cool is that?

I hope someone tries this experiment with bonobos too. And children (against other children with raisins, not child vs. bonobo).