Thursday, September 29, 2005


Above is a picture of the parasitic tapeworm Taenia crassiceps I thought i would post it becuase it is a neat picture. This parasite does look horrifying but there is some evidence to suggest that these and other parasites can be beneficial, manipulating the host immune response and preventing diseases such as asthma. Although a reduction in worm infection is probably not the only reason for the recent dramatic rise in asthma and other inflammatory diseases.

Microscopy and the helminth parasite (source of image)

Parasite role reversal: worms on trial

Wheeze, allergic sensitization and geohelminth infection in Butajira, Ethiopia. doi:10.1111/j.1365-2222.2005.02181.x - evidence contra to the beneficial effect of worms?

Tuesday, September 27, 2005

The social bond between dogs and people

An interesting article on the history of the human relationship with dogs is soon going to be published in the Journal of Archaeological Science. Based on the earliest deliberate burials of humans and dogs it is estimated that this relationship was established by 14,000 years ago, although molecular techniques put this date much earlier. Humans certainly seem to have a strong bond with dogs and dogs have been shown to understand human cues such as gaze direction extremely well. This ability is better than that of the great apes or human reared wolves.

Even though this bond is strong it seems that this ability is quite easy to breed. A Russian experiment with silver foxes has managed to domesticate them in around 30 generations merely by selecting those that showed the least fear of humans. This has lead to a number of other interesting changes including an increase in: ‘floppy ears’ ‘curly tails’ a white star on the forehead and short rolled tails. These traits are also common in domesticated dogs. This shows how easy it is to domesticate an animal, although I wonder what would happen in a non canid?

It is also interesting to speculate why dogs were domesticated in the first place. I am inclined to think it was something like dogs being useful to track or herd animals. But the stability of this relationship for 14,000 years is probably in large part due to the close relationship human and dogs have developed, based on the ability of our two species to communicate in a unique way.
Burying key evidence: the social bond between dogs and people
Darcy F.
Morey. Journal of Archaeological Science.

People have been burying or otherwise ritually
disposing of dead dogs for a long time. They sometimes treat other animals in
such a fashion, but not nearly as often as dogs. This presentation documents the consistent and worldwide distribution of this practice over about the past 12,000e14,000 years. Such practices directly reflect the domestic relationship between people and dogs, and speak rather directly to the timing of canid domestication. In doing so, they contradict recent genetics-based inferences, thus calling into question the legitimacy of focusing mostly on genetic factors
as opposed to other factors. This discussion seeks to work towards a sound framework for analyzing and thus understanding the social compatibility between people and dogs. That compatibility is directly signified by the burial of dogs, with people often responding to the deaths of individual dogs much as they usually respond to the death of a family member. Moreover, that special social relationship continues, as illustrated clearly by the establishment, maintenance, and ongoing use of several modern dog cemeteries, in different countries of the world.

Early Canid Domestication: The Farm-Fox Experiment

Dogs respond appropriately to cues of humans' attentional focus

Saturday, September 24, 2005

Transitional Dinosaur - Bird Eggs

Evolutionary trends in eggs and egg-laying from basal archosaurs to modern birds

An interesting new article is available from Naturwissenschaften reporting the discovery of eggs with dinosaur-like and bird-like characteristics. This is of course exactly what you would expect to find if birds had evolved from dinosaurs.

Minute theropod eggs and embryo from the Lower Cretaceous of Thailand and the dinosaur-bird transition

Eric Buffetaut, Gerald Grellet-Tinner, Varavudh Suteethorn, Gilles Cuny, Haiyan Tong, Adrijan Košir, Lionel Cavin, Suwanna Chitsing, Peter J. Griffiths, Jérôme Tabouelle1 and Jean Le Loeuff.


We report on very small fossil eggs from the Lower Cretaceous of Thailand, one of them containing a theropod embryo, which display a remarkable mosaic of characters. While the surficial ornamentation is typical of non-avian saurischian dinosaurs, the three-layered prismatic structure of the eggshell is currently known only in extant and fossil eggs associated with birds. These eggs, about the size of a goldfinch's, mirror at the reproductive level the retention of small body size that was paramount in the transition from non-avian theropods to birds. The egg-layer may have been a small feathered theropod similar to those recently found in China.

Link - journal website

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