Evidence for Evolution- Parasites Quiz

Answer: Most creationists claim that they are degenerate forms, when in fact they are not

Creationists claim that parasites are degenerate creatures. Under creationist philosophy, creatures can change by degeneration or "devolution," (they can lose information/complexity) they just cannot evolve (which creationists think requires new information/complexity.) However, parasites have not "devolved." They have indeed lost organs and functions that no longer improve their survivability (just as human no longer have tails, fur or a big cecum) but they have also gained incredibly intricate complexity over their ancestors in such matters as their ability to thwart the host's immune system, their reproductive patterns, and their ability to sense and navigate through their hosts.

Creationists have "answers" for the other three issues. They claim that, before the Fall, parasites were innocuous creatures. After the Fall, according to creationists, they somehow went "wrong" and started invading the wrong hosts, the wrong organs, etc. They claim that parasites survived the Flood by becoming spores, going dormant, being frozen in ice floes, etc. Parasites such as fleas and lice are mentioned in the Bible.

Answer: Animals have defense systems to ward off parasite infestation

Again, creationists believe that since creation, only "devolution" has occurred. In this case, sophisticated immune systems, for example, are very difficult to explain. They are useless- in fact they are harmful- if no parasite infestation exists to be fought.

As an example, an immunoglobulin called IgE causes allergic reactions in humans- our bodies react to ragweed pollen, let us say, as a foreign parasite, and the immune system's intense response to "destroy the invader" causes the allergic symptoms we all know and hate.

However, IgE serves a very important purpose in much of the world- it also fights multicellular parasites that we rarely encounter in developed countries. In countries without such parasite problems, IgE is a nuisance. So, immune system responses don't do animals much good if there is no real threat to respond to.

Therefore, the creationist must explain where they came from. Did animals have them before the fall, and suffer the allergies and immune-mediated disorders that an under-exercised immune system causes? Or did they come about only after the Fall- in which case, true evolution, as in increasing complexity, did occur?

Answer: False

In fact, over half of all living animals species are parasitic! Almost all of the many phyla of worms are parasites, as are many insects and arachnids. Keep in mind that many parasites are host-specific- they can live on only one species or genus of animals. And many species have more than one host-specific parasite!

Answer: It contains cell organs that were once part of a bacterium

Plasmodiums contain chloroplasts, the structure that allows photosynthesis in plants, algae, and some bacteria. Genetic analysis has shown that ancestral Plasmodium did not evolve these chloroplasts, they incorporated bacterial chloroplasts into their cells.

A similar phenomenon occurred in animals, which acquired the mitochondria that cells use to produce energy from a bacterial precursor in much the same fashion.

Answer: The Amazon River once emptied into the Pacific Ocean rather than the Atlantic

The tapeworms that parasitize Amazon stingrays have as their closest relatives tapeworms found in the Pacific Ocean. They are not related to the tapeworms found in rays in the Atlantic, where the Amazon now empties. In addition, there are other species of tapeworms found in stingrays in the Atlantic and Pacific that are more closely related to each other than to the tapeworms in the freshwater rays.

The geology of South America can explain this otherwise-odd occurrence quite neatly. Until the Miocene uprising of the Andes Mountains about 10 million years ago, the Amazon flowed into the Pacific, and was colonized at this time by rays from the Pacific. At the same time, there was an open channel through the area that is now Panama that connected the Atlantic and Pacific, allowing rays from both oceans to mingle. As the Andes and the isthmus of Panama arose, the Amazon began to flow into the Atlantic, and the channel allowing intermixing was cut off. But the ray's parasites remain as a record of how the world once was.

Answer: Australia

70 million years ago, Australia and South America were part of the same continent, Gondwanaland. As they drifted apart, marsupials, which originated on that supercontinent, were left on both land masses- along with their parasites.

Answer: Hyenas and lions

This relationship supports an African origination for humans. All tapeworms go through a two-stage life cycle. One stage lives in an herbivore, such as a gazelle or a zebra. The second, reproductive stage lives in a predator, such as a lion or wolf. By scavenging hyena and lion kills, humans ingested the first stage of tapeworms evolved to reproduce in lions and hyenas.

Some of these tapeworms managed to survive, reproduce, and become tapeworms dependent on humans.

Answer: Feather lice

The feather lice (suborder Mallophaga) evolved in the early Eocene, just as most modern families of birds were evolving. Feather lice are usually associated with a specific species or genus of bird. They are such specialized parasites that many species are found only on a certain part of a specific species of bird's anatomy!

Feather lice have been used to determine evolutionary relationships between several families of birds. Closely-related bird families have closely-related louse species; as bird families evolve, their lice evolve with them. As some examples, the lice of flamingoes have been used to determine that flamingoes are more closely related to ducks and geese than they are to cranes and storks. Flamingo lice were more closely related to duck lice than to crane lice, and DNA analysis of the birds proved the hypothesis that this meant that flamingoes were more closely related to ducks than to cranes.
Another study showed that the lice of albatrosses and shearwaters (family Procellariformes) were closely related to the lice of penguins (family Sphenisciformes), showing an evolutionary relationship between these two families.

Answer: Rafflesia has acquired genes from its host plant

Scientists studying Rafflesia were puzzled because genetic analysis of Rafflesia showed that it had similarities both to plants of the order Malpighiales (a large order including many diverse plants such as willows, magnolias, and poinsettias) and the order Vitales (the grapes and their relatives.) Further study showed that the Vitales gene sequences were acquired, through horizontal gene transfer, from its host plant, Tetrastigma (chestnut vine.)

Answer: Genetic relationships between species of Pneumocystis mirrored the relationships between the monkey species

The researchers found that, for example, the pneumocysts found in one species of macaque were more closely related to those found in other species of macaques than to those found in squirrel monkeys. All pneumocysts of Old World monkeys were more closely related to each other than to any pneumocysts found in New World monkeys. Pneumocysts found in humans were more closely related to those found in Old World monkeys than to New World monkeys. Pneumocysts found in lemurs were only distantly related to those found in monkeys. All of this shows that the ancestral pneumocysts infected the ancestral primate, then evolved along with the primates as they diverged.