I went to the museum today, and encountered a few questions I thought I’d share.
How does camouflage evolve?
“The key is that evolution takes small steps over time. The ancestral Eastern tiger swallowtail caterpillar probably looked nothing like a bird turd, and its predators probably completely ignored bird turd as a source of food. In this population any mutation that occurred which made one caterpillar look 2% more turd-like than the others would give that caterpillar a greater chance of survival, as predators would be a little more likely to discount it as a food source. That caterpillar would grow up, reproduce, its offspring would look 2% like a turd and the cycle repeats. Eventually the 2% turd mutation would spread throughout the population. As it becomes more common there would be selective pressure on the predator to identify things that look slightly poo-like as potential food sources. This means that if a second mutation occurred which made the caterpillar look 5% like a turd it would then spread in the same way. Selection would then favour birds able to identify these caterpillars. This could then repeat until we end up with caterpillars that look almost 100% like a bird poo and predators that can tell the difference between a 99% bird poo-like caterpillar and a real bird poo.” –Charles Darwin & Evolution
That’s all fine and dandy, but still, how does the creature know what it should look like?
For mimicry, or on a more general scale, Crypsis to happen, the creature that changed its appearance would need information. Information is something that (as far as we know) insects, animals, etc. don’t have the ability to get. Iyner, on “The Naked Scientists”, states that probability could be at work: “What is the essential difference between that scenario and the arrival of a similar characteristic through two different paths?”
Gavin, on biology-online, says: “Maybe the missing element here is that bugs exist in populations. Variable populations. Reproductive success is at the heart of evolution, and it is reproductive success relative to the other members of the population that is important. If a bug is slightly greener than all the other bugs, it will have a slightly better chance of surviving and reproducing when spending its time, moving or not, amongst green leaves, thus passing along its slightly more greenishness. Maybe that first slightly greener bug got eaten anyway before reproducing. Fast forward a thousand years. A second slightly greenish bug appears but doesn’t get eaten. Slight greenishness is now established in the population. Further mutations may then, over time, improve the greenishness. Later, or concurrently, other variants arise in the population that modify behaviour or body length or morphology that allow those bugs to survive better than others in the population. These new traits then get established in the population.”
But again, this doesn’t answer the question of how it knows what to look like. Maybe I’m over thinking this, but mutations don’t happen all that often. So, how does something adapt to its environment so flawlessly, but so slowly? If it’s left to randomness, to some mutation happening, and benefiting the creature by it not getting eaten, then it would still take a vast amount of time for the population to be completely overrun by the same characteristic (if its even possible for all of the population to change). It would have to be a slow process, and I don’t see how so many different creatures could all survive, and expand their population, based on this theory. Basically, the best explanation we have is of this flawed randomness. I’m skeptical.
How do archaeologists decide where to dig?
Thinkquest says, “Archaeologists look for artifacts at places where prehistoric people probably lived. Early people needed shelter, water, and food, just as we do. So, archaeologists look in caves, near water, in forests, etc. to find things prehistoric people made or had while they were living.
As time passed on, people started living in villages, towns, cities, etc. That is why archaeologists also look at sites of ancient cities. Tombs and sunken ships are also places of many artifacts. It is hard to believe, but areas of destruction from wars can also be sites of many ruins and artifacts.
First, archaeologists do a survey, because it is very expensive to do excavations, and they want to make sure there will be artifacts at the site. The survey includes looking for mounds, foundations, and other visible structures and collecting potsherds. They draw maps and charts and take photographs of the area. They do surveys before people destroy the site by building buildings, houses, and roads, because after the site is destroyed, no one will ever learn about the site.
The second thing archaeologists do is find the artifacts or other signs of behaviour, such as holes for storage, burial, or shelter. This can be done many ways. The most common way is doing an excavation. Another way is making test pits. All of the dirt removed is carefully screened. The dirt falls through the screen, but the artifacts stay.” Also, random people can come across artifacts and will alert archaeologists to the discovery.
When did people decide to have pets, and what made them decide to breed “friendlier” animals?
We honestly don’t know. We do know that people have kept animals around for various purpose, ie. firstname.lastname@example.org says: “Cats were used for rodent control, dogs for various uses (herding, hunting, guarding, etc.). I suppose some rich people (Pharaohs, Roman Emperors) kept individual cats or dogs strictly as a pet, but the majority of the species was still a working animal.” Pets probably came about either by the domestication of wild animals (over time, as they spent more time around humans) which would lead to more affection being placed in them and less potential productivity, or by an animal giving birth and the whole “Mommy can I please keep him??” scenario.