Archive → September, 2008
Why do dogs sometimes eat poop?
Well, the technical term for “poop eater” is Coprophagia and its most common in much smaller animals. Some insects consume and redigest the faeces of large animals which contain substantial amounts of semi-digested food. (Herbivore digestive systems are especially inefficient.) The most famous faeces-eating insect is the dung-beetle and the most ubiquitous is the fly.
Bigger animals too. Capybara, rabbits, hamsters and other related species do not have a complex ruminant digestive system. Instead they extract more nutrition from grass by giving their food a second pass through the gut. Soft caecal pellets of partially digested food are excreted and generally consumed immediately. They also produce normal droppings, which are not eaten.
Young elephants, pandas, koalas, and hippos eat the faeces of their mother to obtain the bacteria required to properly digest vegetation found on the savanna and in the jungle. When they are born, their intestines do not contain these bacteria (they are completely sterile). Without them, they would be unable to get any nutritional value from plants.
Gorillas eat their own faeces and the faeces of other gorillas.
Hamsters eat their own droppings, which are thought to be a source of vitamins B and K, produced by bacteria in the gut. Apes have been observed eating horse faeces for the salt content. Monkeys have been observed eating elephant faeces. Coprophagia also has been observed in the naked mole rat.
But DOGS. What about DOGS…
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Why we can’t clone dinosaurs from mosquito blood
Scientists have argued that much of the Jurassic Park’s (both book and film) content is impossible for various reasons, most notably the suggested means of recovering dinosaur DNA from mosquitoes trapped in fossilized tree sap. While this theory is largely a plot device by Michael Crichton (the author), both novel and movie sparked debate on the feasibility of cloning dinosaurs.
Three arguments why it would not be possible to obtain dinosaurs with this process are summarized thus:
- Dinosaur DNA would be very difficult to correctly sequence without a complete, intact DNA strand for comparison. It would be unlikely to find a complete sequence because DNA is typically unstable outside living organisms (unless it is in the proper buffer).
- Any gaps in the resulting DNA sequence must be filled with dinosaur DNA; using frog DNA as the story suggests would likely produce an organism that varied from the original animal.
- In order to clone a complete DNA sequence, an oocyte from the same organism is required. Since no Mesozoic dinosaurs are alive today, this would be impossible.
Furthermore, it is likely that any prehistoric DNA obtained from a fossilized mosquito would have become contaminated with the mosquito’s own, again making it problematic to clone an ‘accurate’ and viable organism.
A theme expressed throughout the story and its sequel is that of homeothermic (warm-blooded) dinosaurs, a then-recent theory popularized by paleontologist Bob Bakker. While the cinematic adaptation of Jurassic Park used ostrich eggs as vessels to facilitate expression, the novel described “a new plastic with the characteristics of an avian eggshell.” The plastic was called ‘millipore’, invented by an eponymous company subsequently bought by InGen (Millipore Corporation is also the name of a real company that manufactures materials for use in biological sciences, although they are not known to make dinosaur eggshells).
Another note, most of the dinosaurs featured in the novel are not from the Jurassic period; they are actually from the Cretaceous period, the last period during which non-avian dinosaurs lived. However, this may be chalked up to an ignorant or naive marketing decision on InGen’s part.
