Leaving the Wrong Impression

Just when you think everything has gone really well, a student asks a probing question and you are left with the sinking feeling that there was a major disconnect. There are certain choices of words, phrases, and even activities that, without a bit of care, may leave students with the wrong impression.

 

Evolution as improvement
Referring to evolution as progress, or improvement, or getting more sophisticated, implies that the story of life has a directionality, which it does not.

Survival of the fittest
A better way of expressing this idea is “survival of the fit enough.” Portraying nature as “red in tooth and claw,” wherein living things always engage in a life-or-death struggle against competitors grossly oversimplifies what is really going on. Many life forms get by for eons by existing in niches that other organisms are not suited for. For example, brine shrimp live in water that is unsuitable for potential aquatic enemies, and they apparently have no significant competitors for food.

Time lines
The time lines that are commonly seen on classroom walls often show a sequence such as bacteria-jellyfish-trilobite-dinosaur-mammoth. These timelines may give the impression that disparate forms evolved into each other. Clearly, these timelines are intended to show the dominant life forms during geologic eras, but they could mislead. A more appropriate timeline, conceptually, would be one that includes transitions and thus shows evolution rather than replacement.

The tentative nature of science
Scientists will acknowledge that their results are always tentative. This does not mean that their ideas are poorly supported but that science is always ready to modify or reject ideas as new information is acquired. Tentativeness reflects an attitude of honesty and openness, not weakness of argument.

Misunderstanding of the time involved in
the Cambrian explosion

The Cambrian “explosion” is an unfortunate misnomer, as it is not an example of life forms springing forth fully formed, virtually in an instant. The fossil record of the early Cambrian contains a large number of animals with hard parts, which preserve rather well. This is the earliest good record of a fauna that had evolved over millions of years. It was a very slow explosion.

Names like silverfish, starfish, jellyfish, crayfish
Early discoverers of life on Earth seemed to run out of vocabulary. A fish is anything that lives in water, except a silverfish, which lives in cupboards. Some terms are used over and over, leading to much confusion in the minds of students and other people. There are two potential solutions to this problem: first, we can refer to jellies, sea stars and crawdads instead of jellyfish, starfish, and crayfish. Second, we can use scientific terminology. Refer to cnidarians, echinoderms and crustaceans. It’s a problem and it’s your call.

Apes without humans
Humans and chimpanzees shared a common ancestor about six million years ago. This was after the human/chimp ancestor had branched off from the line that led to gorillas and long after the human/chimp/gorilla line branched off from the line that led to orangutans. So, to lump chimps, gorillas and orangutans together as “apes” without including humans is an artificial grouping.

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Keeping Up with the Times


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