Every Day Is Special: evolution

Showing posts with label evolution. Show all posts

November 10 - Happy Birthday, Francis Maitland Balfour

Posted on November 10, 2021

This is an update of my post published on November 10, 2010:

Born in Great Britain on this day in 1851, Francis Maitland Balfour became a biologist and made contributions in the fields of embryology, morphology, and evolution. Sadly, Balfour's career was cut short when he died trying to climb the highest mountain in the Alps, Mont Blanc.

Embryology is the study of the development of embryos—that is, animals before hatching or birth (or plants before germination).

Morphology is the study of the form and structure of animals (and plants). It's rather like comparative anatomy.

Evolution, as I am sure you know, is gradual change over time. In this biological context, evolution means gradual changes in the forms and lifestyles of animals (and plants and other living things) over the course of thousands and millions of years.

Human and Pig Embryos

Balfour pointed out that vertebrates (animals with backbones) and some invertebrates (animals without backbones) are obviously related because they all have notochords (flexible rods of cells extending down the body) when they are embryos. He agreed with some scientists of his time that the development of an embryo tends to go through the various forms that the organism's ancestors had during the evolution of that organism. This theory is called recapitulation, and today it is considered an oversimplification and therefore inaccurate.

Here is a case in which recapitulation does not happen: A chicken and a lizard look more alike at certain early stages of embryonic development than they do as adult animals. This is not surprising since chickens and lizards have common ancestors if you look back far enough. Chickens and all other birds evolved from reptiles, specifically dinosaurs, which of course had teeth. But chickens do not go through a stage as embryos in which they have teeth. (They do, however, have the genes for teeth and can be made to grow teeth if we manipulate those genes to “turn them on.”)

In some cases animals' evolutionary stages do seem to be echoed by their embryonic stages. For example, whale embryos begin to grow legs that later disappear. Whale embryos also grow hair that is later lost.

These whale embryos show that whales begin to have
leg "buds," like other mammals, but they do not grow
actual legs.

Watch embryos develop!

Have you ever considered incubating chicken eggs? Here is a website that explains how to “candle” eggs so you can see the developing chicks.

Check out human embryology with The Virtual Human Embryo. Click on each picture to get a close-up and a description of that stage.

Also on this date:

World Science Day for Peace and Development

Maputo City Day

Rebenlichter in Switzerland

U.S.Marine Corps's birthday

Sesame Street's birthday

Biologist Francis Maitland Balfour's birthday

Area Code Day

Windows Day

First Cry of Independence in Panama

Anniversary of a the Hope Diamond gifted to the Smithsonian

Charmed Quark Day

Heroes Day in Indonesia

Geographic Information Systems Day
(Second Wednesday of November)

Plan ahead:

Check out my Pinterest boards for:

November holidays
November birthdays
Historical anniversaries in November

And here are my Pinterest boards for:

December holidays
December birthdays
Historical anniversaries in December

April 18 - Commemorations in Science

Posted on April 18, 2021

This is an update of my post published on April 18, 2010

April 18, 1857 - Clarence Darrow born in Ohio, U.S.

Clarence Darrow was a lawyer, not a scientist, and his most famous case was defending a teacher, not a scientist.

So why is this a commemoration in science?

Well, Darrow was the lawyer who defended John Scopes in the famous “Monkey Trial” over the teaching of evolution in public high schools. A Tennessee law called the Butler Act was passed in 1925. This statute made it unlawful to teach any ideas about the origin of humanity other than "the Biblical account."

And "the Biblical account" basically meant one particular interpretation of one particular translation of some very ancient writings - an interpretation adopted by only some of the practitioners of one particular sect of one particular religion!

Public schools are actually a part of the government - even in Tennessee. And the U.S. Constitution clearly states that, in this nation, there can be "no law respecting an establishment of religion, or prohibiting the free exercise thereof." In other words, the government and its institutions cannot favor one religion over another, or religion in general over lack of religion.

Mandating that public schools teach the beliefs of one particular version of Christianity as fact waaaayyyy breaks that rule.

Immediately some people began to plan to intentionally break the law to make sure that there would be a trial in which the law could be declared unconstitutional. A biology teacher named John Scopes was just doing his job when he taught evolution from the textbook that the state had mandated that he use, but he agreed to be a part of this test case, even though it would mean that he would be arrested. (He was never actually taken into custody, and the bail was paid by the owner of a newspaper.)

I read that a lot of people in the nation listened to the trial
on the radio, a lot read newspaper reports about the
trial (although I think that journalism was pretty un-trust-
worthy at that tie), and a lot of people actually went to Dayton,
Tennessee, where the trial was held!

Apparently so many people went to Dayton, there was a carnival
vibe to the town. There were even sideshows for visitors!

Clarence Darrow defended Scopes on several grounds. He lost the case but was able to win lots of points with large sections of the public, who listened to the trial on the radio and read reports about the trial in newspapers. When the case was appealed, the “guilty” verdict was set aside.

For older students, there is lots of information on the trial on this website.

Another article discusses the play and later movie inspired by the trial, Inherit the Wind. (The play and movie are very much *not* accurate portrayals of the trial, and were never intended to be. They are fiction that was inspired by the actual trial.)

If you want to know more about human evolution (part of what seemed to be on trial during the Scopes trial), check out these videos.

April 18, 1872 – Bernard O. Dodge born in Wisconsin, U.S.

Dodge was a botanist who pioneered research on heredity in fungi. He was the first to study sexual reproduction of common bread mold, Neurospora.

Hopefully, you are asking - wait, how DOES bread mold reproduce?
This diagram shows the structures of "eating" (absorbing nutrients)
and reproducing (making offspring, as in more bread mold).

April 18, 1955 – Albert Einstein dies in New Jersey, U.S.

Einstein was the German-born physicist who came up with some of the most important theories of the 20th Century, including the theory of relativity. For more on Einstein, check out this March posting.