Giant bug fossil found

A fossilized claw of a 8 feet long sea scorpion, living 390 million years ago, has been discovered. This is the largest insect ever discovered according to the article, though it's speculated that Arthropleuridae could be as long as 10 feet.

The paper about the discovery can be found at the Royal Society's Biology Letters (link to abstract), which unfortunately is behind a pay-wall.

Altruism in wasps tied to maternal behavior

ScienceDaily reports on an interesting study of wasps, where to researchers took a look at the genes of the different types of wasps, and saw if there was any connection to their genes.

Altruism Evolved From Maternal Behavior, Wasp Genetics Study Suggests

Researchers at the University of Illinois have used an innovative approach to reveal the molecular basis of altruistic behavior in wasps. The research team focused on the expression of behavior-related genes in Polistes metricus paper wasps, a species for which little genetic data was available when the study was begun.

Like honey bee workers, wasp workers give up their reproductive capabilities and focus entirely on nurturing their larval siblings, a practice that seems to defy the Darwinian prediction that a successful organism strives, above all else, to reproduce itself. Such behaviors are indicative of a eusocial society, in which some individuals lose, or sacrifice, their reproductive functions and instead work to benefit the larger group.

I don't get the use of 'Darwinian' unless it refers to some predictions made by Darwin. Even if it does, the reference to the prediction seems a bit weird, as it has long been known that evolution works on the species level, so it's not important if one particular individual reproduces, but rather that the species on the whole, reproduces in the most efficient way possible. For some species that apparently involves "a eusocial society" (an expression I've never heard before).

The researchers found that the pattern of behavior-related genes expressed in the brains of worker wasps was most similar to that seen in foundresses, the female wasps who alone build new colonies and devote much of their early lives to maternal tasks.

"These wasps start out as single moms," said postdoctoral researcher Amy Toth. "They don't have any workers to help them, so they're responsible for laying all the eggs and provisioning the developing larvae which then turn into workers."

The researchers selected this species because it appears to represent an evolutionary transition. Once a foundress has raised a first generation of workers, she turns over the task of nurturing the larvae to the workers and devotes herself entirely to her "queenly" reproductive function.

At this point, the researchers discovered, behavioral gene expression in her brain changes, becoming distinct from that seen during her maternal period.

Toth noted that the P. metricus wasps represent a kind of intermediate stage in the evolution of eusocial behavior. The honey bee colony, in which queens never perform maternal tasks, is considered a more developed form of eusociality.

So, queens have a different behavioral gene expression than foundresses, who are more similar to workers in their expression than queens and gynes (future queens in existing colonies). So, in other words, worker wasps (bees, etc.) are more maternal even though they are unable to sexually reproduce.

That's quite interesting.

It does not follow that all observed altruistic behavior have roots in maternal (or paternal) behaviour, but it would follow from what we generally know about evolution.

The study can be found here (behind a paywall)

Drooling cockroaches

Ok, I guess the correct title should have been salivating cockroaches, but that doesn't sounds as cool - and anyway, the best title was already used by PLOS One: Pavlov's Cockroach by Hidehiro Watanabe and Makoto Mizunami

The two Japanese scientists have studied the salivation of cockroaches, and how those could be activated by specific odors, that the cockroaches associated with food. This study is of course very similar to Pavlov's classic study of a similar mechanism in dogs (used sounds instead of odors).

The interesting part of this study, is that the mechanisms behind the salivation is little understod, and had so far only been observed in Humans and dogs.

Secretion of saliva to aid swallowing and digestion is an important physiological function found in many vertebrates and invertebrates. Pavlov reported classical conditioning of salivation in dogs a century ago. Conditioning of salivation, however, has been so far reported only in dogs and humans, and its underlying neural mechanisms remain elusive because of the complexity of the mammalian brain. We previously reported that, in cockroaches Periplaneta americana, salivary neurons that control salivation exhibited increased responses to an odor after conditioning trials in which the odor was paired with sucrose solution. However, no direct evidence of conditioning of salivation was obtained. In this study, we investigated the effects of conditioning trials on the level of salivation. Untrained cockroaches exhibited salivary responses to sucrose solution applied to the mouth but not to peppermint or vanilla odor applied to an antenna. After differential conditioning trials in which an odor was paired with sucrose solution and another odor was presented without pairing with sucrose solution, sucrose-associated odor induced an increase in the level of salivation, but the odor presented alone did not. The conditioning effect lasted for one day after conditioning trials. This study demonstrates, for the first time, classical conditioning of salivation in species other than dogs and humans, thereby providing the first evidence of sophisticated neural control of autonomic function in insects. The results provide a useful model system for studying cellular basis of conditioning of salivation in the simpler nervous system of insects.

Quite interesting, and hopefully something that will give us a better understand of how brains work.