Testing a Hypothesis: Sometimes It's Your Only Choice

Plants are dynamic beings that respond continuously to their environments. (Continuous means without interruption, while continual means at recurring intervals.) That is, plants adjust their growth, and even their movements, all the time, day and night, all year.

One fascinating example is called nyctinasty. This is where a plant raises its leaves up, or opens its leaflets, during the day, and lowers the leaves or closes the leaflets at night. Makes sense. During the day they need the light for photosynthesis, and at night they don’t.

Problem is, most plants don’t bother opening and closing, or raising and lowering, their green surfaces. The leaves face the sky in the day, but at night, most plants just leave them where they are. Only a few plants raise and lower, or open and close, their leaves. Examples include the velvetleaf Abutilon theophrasti and many members of the bean family, including the mimosa tree Albizzia julibrissin. This photo shows mimosa leaves folding up for the night, even before sunset. Each mimosa leaf consists of leaflets, each of which has lots of little pinnules. It is, as you can see, the pinnules that close up, and they do so by moving upward.

Why should a plant fold up its leaves at night? Nobody knows, but there is plenty of speculation. Some think it protects the leaves from nighttime rain; others say it hides them from bugs. The most likely reason is that the night sky can be very cold, any time of year, even if the air is not. This could cause the leaves to get too cold during the spring (or fall, but autumn leaves have little value to a deciduous plant that is going to drop them anyway). This was Darwin’s idea, and (working with his son Francis) he made the observations to support (but not to prove) it. Of course, this doesn’t explain why the other plants don’t do this.

This is what mimosas do during under regular conditions: they raise their pinnules each sunset and lower them each sunrise. They do so by the alternate swelling and shriveling of little sacs called pulvini (singular pulvinus). But what I wanted to know was, is the pulvinus on the top side of the pinnule stalk, in which case the pulvinus swells to push the pinnule down, and the pinnule moves up when the pulvinus shrivels; or is it on the bottom of the stalk, in which case it pushes the pinnule down when it swells, and the pinnule moves up when the pulvinus shrivels. The swelling of the pulvinus requires energy; the shriveling does not. Therefore, I wondered, does the pulvinus push the pinnule up at dawn, or does it push it down at sunset?

I looked in the scientific literature and all over the web, and (at least in 2018) could not find an answer to this simple question. So, in desperation, I decided to test a hypothesis myself. And I did so without any fancy equipment or a research grant.

Nyctinasty is not the only process that can make a pulvinus shrivel. Drought can also make a pulvinus shrivel, just as it can make every other cell or structure in a plant shrivel.

There happened to be a drought going on in Tulsa, where I live, in summer 2018. So I went looking for a mimosa tree that was experiencing drought. I had to go up on Turkey Mountain (which is a hill and has no turkeys) to find one. As you can see from the photo, a mimosa leaf experiencing drought during the day raises its pinnules before they start to curl up. This means that the pulvini must be on the top of the pinnule stalks. The pinnules lift up because of tension in the cellulose fibers in the cell walls, unless pulvini push them down.

I wanted to know the answer to the question, but I found enjoyment in answering the question in a way that anyone can do, even without a laboratory.

Another question that you might wonder about is this. After you exercise, of course, you breathe faster, and this helps your body to get rid of carbon dioxide that has built up in your blood. But does each breath have more carbon dioxide? To answer this question, all you need to do is to blow bubbles in slightly basic water. The water should contain some phenolphthalein, which turns pink under basic conditions, and turns clear in acid conditions. If each breath has more carbon dioxide (which becomes carbonic acid in water), then the phenolphthalein should turn clear sooner when you blow bubbles in the water right after exercising than when you blow bubbles in the water while rested. You can answer this physiological question, about lungs and carbon dioxide, without any equipment other than two glass jars, a couple of straws, and a little phenolphthalein. (You can’t just walk into the drug store for phenolphthalein, but it is not a controlled substance. You get it from science education supply companies.) If you can’t afford a carbon dioxide measuring device, you can test the hypothesis in a cheap and easy fashion.

These are actually experiments. In the case of the mimosa, it is a natural experiment: nature imposed the drought on the plants. In the case of breathing, the experiment compares the treatment (breath after exercise) against the control (breath while resting).

And it’s fun, too. Students like it. If you are an elementary school teacher, you can do the bubble experiment in your class.

There are probably lots and lots of questions that you wonder about and for which you cannot find an answer. Rather than to give up, try finding the answer by some simple observation or experiment.

Natural Selection and Slavery

I have been reading the book about runaway slaves by John Hope Franklin and Loren Schweninger. It is an overwhelming book because it contains literally hundreds of stories of runaway slaves in nineteenth century America, with names and whatever scant details may be available from the historical record. The authors attempt some generalizations, but it is very clear that each slave’s story was individual and unique. And the documented brutalities are unspeakably painful.  I considered myself knowledgeable about American history, but this book took my breath away. No wonder the late John Hope Franklin is so famous among scholars and non-scholarly readers alike. This is the painting by Thomas Moran, who lived during this time, which is in the Philbrook Museum in Tulsa, where I live, and that was on the cover of the book.

And here is a photo of John Hope Franklin.

As a biologist specializing in writing and educating about evolution, I noticed a generalization that even the late great John Hope Franklin did not, and it has directly to do with evolution by means of natural selection.

Slaveowners and hunters believed passionately that slaves, and black people in general, were inferior in intelligence. Despite this, the racist whites of the South did their best to subject their slaves—and even free blacks, whom they sometimes kidnapped—to deprivations that were clearly intended to keep them physically and mentally inferior. In particular, they seldom allowed their slaves to learn to read and write (a literate slave could write out documentation that said they were free, for example), or to learn simple arithmetic, or to learn to read a map (which could help them to escape, if they should happen to get hold of a map).

Despite this, the runaway slaves proved themselves to be extremely intelligent and clever. As a matter of fact, the deprivations forced upon them by the whites selected for the most intelligent and clever slaves. The only way a slave could be successful was by outplaying their white overlords at their own game. One example that sticks in my mind is the slave who, on his escape route, asked a white train operator which train went to Raleigh. The slave knew that word would soon get around about his escape, and with his description. Asking the train operator how to get to Raleigh was a trick. The slave had no intention of going to Raleigh, but his question would mislead his pursuers into looking for him in that direction. Clever!

That is, the very ways in which whites oppressed slaves were in fact an evolutionary pressure leading to greater intelligence, over the generations, in the slave populations. Not only were black people equally intelligent to start with, but the evil efforts of the whites pushed black populations into even greater intelligence.

It doesn’t take any intelligence to be cruel or to be an oppressor. It takes intelligence to escape oppression. To this day, we are left with the image of stupid racists trying to belittle intelligent minorities.

January 6 and the Legacies of Slavery

Can you believe it, I have only now read Uncle Tom’s Cabin? This was Harriet Beecher Stowe’s novel, which began serialization in 1851, about the many ways that black slaves suffered in a country that was still the United States. It is a novel that is today not taken seriously enough, and most of the issues that the book raised remain unresolved. Among the modern consequences of slavery was the domestic terrorism of January 6, 2021.

It is common now for readers to look down upon Uncle Tom’s Cabin. And it is true that this novel could not be published today in its current form. But it played an important role in American history at that time. Stowe pointed out many things that even most northerners did not know about slavery, for example, that slaveowners could abuse their slaves, with no limits, because slaves were property, not people. Few slaveowners killed their slaves, but for those that did, there was no legal consequence. For example, in 1847, a slave owner’s wife murdered two female slaves by bashing their heads in. She was brought to trial. The prosecution, representing the state of South Carolina, called it murder. The defense called it “ordinary domestic discipline.” The judge found in favor of the defense. This was one brief shining moment where slaves might have been considered human beings, and the moment passed.

Slaveowners could break up slave families and sell husbands, wives, and children separately. In fact, there was no such thing as marriage for slaves; slaveowners could dissolve slave marriages and force new ones, just like breeding livestock. Matter of fact, most Americans probably do not know these things even today. Stowe’s mission was to shock America into caring about the slaves and stopping the institution itself. All of the novel’s almost insufferable sentimentality had a direct purpose.

In addition, the title character, Uncle Tom, was completely subservient to his white masters and prayed constantly for their redemption from sin. This is not the image of slavery that we want to believe. We want to believe that slaves were proudly angry at their masters. And most of them probably were, as documented in the writings of historian John Hope Franklin. Slaves like Uncle Tom were rare. Personally, I prefer the slaves who fought back, like Nat Turner. But remember that there were other slaves in this novel who were not so subservient. The way Cassy manipulated Simon Legree was brilliant and heroic. You may pity Uncle Tom, but the way Eliza crossed the frozen Ohio River was worthy of a superhero.

Perhaps most of all, the issues raised by Uncle Tom’s Cabin were not resolved by the end of the Civil War, nor have they yet been. Oppression did not go away, and still has not.

Through most of the history of the United States, the racist South has gotten everything their way, by threat of force against the North. Here is my list:

• When Jefferson wrote the Declaration of Independence, he included a paragraph against slavery. When someone pointed out Jefferson’s hypocrisy as a slaveowner, Jefferson said that he intended to free his slaves. The southern colonies forced the removal of this paragraph, thus giving birth to a United States in which it was legal to own slaves.
• Slaves were not given rights as citizens or even as people, but the Southern states insisted that slaves be counted in the census as three-fifths of a person, thus giving the Southern states a bigger representation in Congress than they would have otherwise had, when the Constitution was ratified.
• For the Southern economy, thus for the American economy, slavery was essential. The economy simply could not have functioned without the use of slave labor, in two ways. First, the slaves worked for free on the plantations themselves. Second, their owners hired them out to work in factories and shops, then kept the wages that the factory and shop owners paid to the slaves.
• This amounted to a big pot of money, without which the South would have gone bankrupt. And it was not just slavery that was essential; it was slaves as an expendable resource that was necessary. The slaves on the southern plantations, “down the river,” lived only a few years before they were worked or beaten to death. Had the downriver slaves lived full lives, however miserable, the slave market would have dried up.
• The northerners did not own slaves, but they were required (by the Fugitive Slave Act of 1850) to turn in any fugitive slaves that they knew about, and certainly not to harbor any fugitive slaves. This is the reason that the Underground Railroad took slaves to Canada, not just to the North. The southern love of slavery forced the north to support slavery.
• When the South lost the Civil War, their economy was devastated. But they did not lose all of their money. The fortunes previously made, and which escaped battlefield destruction, were kept. This was the foundation of Southern corporations and banks. Today, many corporations and banks descended from those of the postwar South remain wealthy and have a major role in the modern American economy, because of the money they got from slave labor.
• Largely because of the direct influence of Southern states, justice has not yet been done regarding the lynchings of black people (in both the North and South) or the Tulsa Race Massacre. Even as late as the centennial of the Massacre, in 2021, most Americans (even me, a Tulsa resident) had not even heard about the Tulsa Race Massacre. Southerners have supported a conspiracy of silence about our recent past affliction of black people.

The flag of the Old Confederacy still flies in America, mostly in the South, and was the direct inspiration for attacks on modern democracy, such as the January 6 attack on the Capitol exactly two years ago today.

America remains tarnished by the legacy of slavery.

"The Bible says..." about Slavery

Fundamentalist Christians universally claim, “The Bible says it, I believe it, and that settles it.” But this statement is, even from a literalistic view of the Bible, incorrect. What they really mean is, “The Bible says it, I interpret it, and that settles it.” The fundamentalist, therefore, puts Himself or Herself blasphemously into the line of authority. They expect us to believe their interpretation as if it were the very words of God. Literalist Bible believers should not do this. Many of them do, which is why I turn away whenever I hear them preaching.

Examples abound and I have written about many of them, both here (about their attacks on science) and in my religion blog. But the example I am thinking of now is slavery; in particular, black slavery before the Civil War in the United States. I have just finished reading Uncle Tom’s Cabin by Harriet Beecher Stowe, the novel that, according to Lincoln, was one of the major causes of the Civil War. In addition, Harriet Beecher Stowe was the brother of Henry Ward Beecher, a famous preacher who stirred up great audiences in the north, and in England, against slavery. Some historians have said that Henry Ward Beecher’s message was an important reason that England supported the north instead of the south, which was a profitable source of cotton, sugar, etc. The southern states had ample reason to hate both of the Beechers.

This novel was written in the hortatory, preachy style found in so many novels of that period. Some of my liberal friends will roll their eyes at it. But it was the novel that captured the attention of most Americans to show that slavery was a complex system of evil that pervaded the economy. This was Harriet Beecher Stowe’s challenge: So, you don’t own slaves? Fine. But you may have invested in businesses that get their money from slavery. And your national laws require you to betray runaway slaves to federal authorities. Slavery was an evil deeply intertwined with the American economy. Many northerners, who could not own their own slaves, supported policies that maintained slavery in the south. These people, Stowe made it clear, were as cruel in their thinking as the slave owners themselves, even the slave catchers.

Many people think that the federal government could not have stopped slavery. The constitution did not delegate that authority to the federal government. It was a state’s right to have, or not have, slavery. This is stupid and evil. Of course the federal government could have done it, via the interstate commerce clause of the Constitution. That is, unless slave owners and sellers could prove that slaves did not cross state lines. As soon as a slave was transported from, say, Alabama into Georgia, the feds could have said, federal anti-slavery laws now apply.

And now consider how slavery relates to fundamentalism. The Golden Rule, as stated in the New Testament, is do unto others as you would have them do unto you. You wouldn’t want someone to whip you, or to steal your wages, or to take your child or wife or husband from you; so don’t do that to anyone else. Seems pretty clear.

But antebellum fundamentalists had some contorted arguments that they considered to be absolutely Biblical. Stowe mentions three, and I have added a fourth:

• One is that Paul told the escaped slave Onesimus to return to his owner, Philemon. This is explained in the Book of Philemon. Never heard of it? Prepare to be surprised.
• Another is, in Genesis, God said, “Cursed be Canaan,” and said his descendants, whom the fundamentalist preacher in the novel said were African, would be slaves.
• Paul also told Christians to be content in whatever state they find themselves. The Southern preachers used this to tell slaves that God wants them to be contented with being slaves.
• Finally, some Biblical scholars came up with a theory that the black race was not really human and found some way or other to justify it with the Bible. This one was not in the novel. But I have known people, within recent decades, who believed this. Of course, this would mean that the black race had to be housed with the animals on the Ark. Fundamentalists don’t have an answer to this. As an evolutionary biologist, I am particularly bothered by this argument, which contradicts all we know about human biology.

To fundamentalist preachers in the antebellum South, these fragile arguments were enough to negate the Golden Rule.

Yes, twisting scripture to make it say what you wish, in utter contradiction to what the God of Love would want, has a long history within fundamentalism. It continues today. I will have more to say about this very soon.