News

Teaching accurate evolution concepts is important for people and the planet November 08 2021, 0 Comments

I have been studying the concepts of evolution and false ideas about this process. “Evolution” literally means “unrolling,” and we use the word as a name for the changes in life over time. I am convinced that children (and everyone else) need to know valid ideas about evolution as a basis for social justice and peace.

The idea that some life is more advanced or important than other life started with Aristotle and Plato. They used an animal-vegetable-mineral classification, which is an intuitive idea that still exists. It leads to misconceptions about how evolution occurs and what it produces.

Aristotle introduced the “scala naturae” or great chain of being, which is a ranking of organisms from “lower” to “higher.” He ranked animals with blood above those without – the invertebrates whose blood he didn’t recognize. Plants, of course, went beneath animals, followed by minerals. Soil was at the very bottom of the scheme, which is the opposite of our current view. Now we see soil as a unique combination of living and non-living, and the foundation and sustainer of life on land.

During the Middle Ages, the idea of a chain or ladder of life became a religious idea as well. At the top sat the deity with the angels beneath, then humans, and so on down the ladder. Religious authorities presented this ordering as divinely given, which likely helped keep those on the lower rungs of social structure down there doing the hard work.

At one time, biologists used the great chain of being concept, and scholars thought that all organisms were striving to improve and move up the ladder of life. When Darwin proposed his theory of evolution via natural selection, he included the idea that there was no direction to evolution. After genetics and molecular biology showed the mechanism of evolution, most biologists accepted the idea that evolution doesn’t have a goal. Some biologists still thought that life was evolving toward complexity or some pinnacle of evolution.

One of the most famous – and wrong – illustrations of evolution shows a monkey, an ape, a caveman, and a modern man marching along from left to right. Note that I said “man” not “human.” This iconic illustration always ends with a Caucasian male. It leaves the impression that white males are the ultimate product of evolution.

There is no pinnacle of evolution, only a many-branched Tree of Life. There are no “highly evolved” organisms vs. more primitive ones. All life in existence is very complex; it has thousands of molecules in a highly ordered arrangement, all functioning together. All extant life has been evolving for the same amount of time although some lineages have undergone more visible changes than others. If life continues to exist, it continues to evolve.

It may seem that evolution produces more complex life, but that is not always the case except for the earliest life. Think of life starting as simple cells. There wasn’t any room to get simpler, but the opportunities to become more complex were plentiful. Even with that, there are many instances of a lineage of life becoming less complex and losing structures rather than developing new ones. This has happened frequently with parasitic organisms, but free-living animals also give up structures. The echinoderm lineage is sister to the chordates, which means that they shared a common ancestor. One branch got more complex and developed vertebrae; the other got simpler and combined several organ systems into a water vascular system. Both are highly successful.

As far as anyone can tell, evolution has no special direction and no goal other than the survival of life, all kinds of life. Especially all kinds of life because it takes diversity for life to continue. There is no climbing to the top, whatever that might be. With no ladder of life, there are no missing links, and paleontologists no longer use that term.

What does this mean in the classroom? The guiding adult must take great care to express the concepts of evolution accurately and to remove any diagrams that give false impressions.

I’ve written previously about the problem of teleology, the idea that organisms change because they want to or need to do so, but it is worth repeating. Fish didn’t decide to try growing legs, and they didn’t get them because they wanted to get out of the water. Those are teleological ideas. If an organism could change because it wanted to do so, there would likely be a lot of three-armed people taking care of small children. 😊

I don’t mean to say that people can’t change; they certainly change their minds and may work to bring about other changes in their lives. Individuals do not evolve, however. Evolution can be defined as a change in the frequency of a trait in a population. The process of natural selection brings about this change. A random mutation can change a trait in an individual organism, but evolution doesn’t take place unless that trait is passed to offspring, AND it confers an advantage for surviving and reproducing.

In the classroom, if children see a Tree of Life diagram that shows humans (or mammals) as a part of the diversity of life, they will have a better perspective than if they see a row of equally spaced boxes with humans/mammals at the far right. If they see a timeline of humans that shows modern humans with a range of skin colors, it will give a more accurate impression of what the evidence indicates has happened. An accurate timeline of humans cannot be a straight line. See https://humanorigins.si.edu/evidence/human-evolution-interactive-timeline for a more realistic view.

A timeline of humans that ends in light-skinned and light-haired people is not fair to anyone. I think it is best if children understand that there are many colors and cultures of humans, and that all of them are equally evolved and equally valuable. You may ask best for what? Best for our species and the whole biosphere.

“Life is a copiously branching bush, continually pruned by the grim reaper of extinction, not a ladder of predictable progress.”

― Stephen Jay Gould, Wonderful Life: The Burgess Shale and the Nature of History

Priscilla Spears, November 2021


Why Montessorians need a new biology album July 28 2021, 0 Comments

Why does the Montessori world need a new biology album? Basically, there are two reasons...

It's time to take out the teleology March 03 2021, 3 Comments

It is imperative that we inspire children with scientifically valid ideas.

Spring cleaning in your biology closet March 04 2020, 0 Comments

It’s that time of year when the urge to put things in order can strike. You may have a closet with a lot of biology materials that you want to evaluate. Here are my suggestions for things to throw out. You may not want to discard the whole material just because it has flawed content provided it is feasible to fix the problems.

In the animal kingdom materials, if you find anything that has the phylum Coelenterata, please remove that name or cover it. Biologists haven’t used it for more than 30 years. That phylum was split into two others when biologists discovered that it held two unrelated groups. The two lineages are called phylum Cnidaria (anemones, corals, and jellyfish) and phylum Ctenophora (comb jellies). It is likely that you can cover over “Coelenterata” and add the label “Cnidaria.” Just make sure that you don’t have comb jellies in with your cnidarians.

Another no-no for the animal kingdom is showing protozoa along with the animals. This goes back to the two-kingdom idea of classification, and biologists and biology textbooks haven’t grouped protozoans with animals in more than 40 years.

If you find a chart that is labeled “Non-Chordates,” change the title to “Invertebrates.” Maybe “non-Chordate” was useful in the past, but biologists use “invertebrate” far more often. I searched books on Amazon.com using “non-chordates,” and I got six titles, all published outside the US. I searched “invertebrates,” and got over 6000 titles. A non-chordate chart isn’t likely to show current information, so it is time to recycle it or at least recycle the images and add new text.

The relationships between the phyla of animals solidified about 15 years ago. In biology, classification has morphed into systematics, which all about relationships and shared common ancestry. The details of this would take several blogs so I will simply say that the arthropods are related to the nematodes, and the mollusks are related to the annelids. Arthropods were once grouped with annelids, but that is no longer considered valid. Can you add something to your animal kingdom chart that shows which phyla are closely related? See my book, Kingdoms of Life Connected, for help if your animal kingdom chart needs a redo. https://big-picture-science.myshopify.com/collections/frontpage/products/kingdoms-of-life-connected-second-edition.  It is also available as an ebook (pdf).

Dig back into the cobwebs in the botany section of your closet. If your chart of the plant has club mosses separated from the fern clade – whisk ferns, horsetails, and ferns – you have a good representation of life’s diversity. The chart from InPrint for Children is a good example. https://big-picture-science.myshopify.com/collections/montessori-botany-materials/products/plant-kingdom-chart . Another mark of a current material – it should use the term “eudicots” instead of “dicots.”  If your chart has phylum names, it is quite possible that many of the names are obsolete. Many botanists no longer use phyla or division names. Instead, they use lineage names, and sometimes a common name is all you need. I have a graduate level botany textbook that uses no phylum/division names. 

If your plant kingdom chart has fungi or bacteria on it, the time has come to do some serious pruning. Those two have to go to their own charts. If the image of a fungus appears on a plant kingdom chart, that’s what children will remember even if you say that it doesn’t belong there. The fungus kingdom is a sister to the animal kingdom. In nature, fungi and plants are partners, but on classification charts, they shouldn’t hang around together.

If you have a Five Kingdoms chart, file it under the history of biology. It should NOT be the first thing children see as they study the diversity of life. The Tree of Life is the place to start.

How about your timeline of life? This is a difficult material to do well, and there are many bad attempts out there. Does your timeline show several red lines coming together (converging)? That’s the traditional style, but lineages do not converge (fuse together); they diverge (split apart). Maybe you could salvage the images and redo the timeline without the misleading lines. Check the dates for the fossils because there are several in the wrong place on the older timelines.

Does your timeline of life have photos of extant animals or plants in prehistoric times? This gives a very wrong impression. I’ve seen a timeline that had “First marsupial” and a picture of a kangaroo. This is just like saying “First eutherian (placental) mammal” and showing a picture of a horse. Both the kangaroo and the horse evolved within the last few million years. They are both adapted to live on grasslands and open shrub lands, where resources are spread out, and there is little cover from predators. Therefore both are good at moving quickly over long distances. Neither one of them belongs in the Mesozoic Era on a timeline of life. Mesozoic mammals were much smaller and less specialized.

Does your timeline have the five major extinctions? And does it have ice ages in the right places? The older charts used ice to symbolize all extinctions, although that wasn’t the cause in most of them. The five major extinctions come at the end of the Ordovician, Devonian, Permian, Triassic, and Cretaceous Periods. They are such important shapers of life that they are essential to a good timeline.

If all this correcting sounds like too much to do, remember that you are doing it for the children. They need current information and a foundation that they can use in their future studies. There is no point in giving them science “information” that they will never see outside a Montessori classroom.


Moving past zoology and botany April 30 2019, 0 Comments

Normally, I write about elementary or secondary education in my blog. In this one, I’m addressing an issue that starts in early childhood, and it affects the way children view the living world in their later studies.

Traditionally, Montessori life science (biology) was divided into zoology and botany. The divide began when young children sorted pictures into animals vs. plants. This exercise fit well with the two kingdom approach to classifying the living world. I certainly hope that Montessori teachers no longer use two kingdoms. Biologists began moving away from two kingdoms in the mid-1800s, although it took a hundred years and major advances in biochemistry and microscopy to complete the break. We can give children a more useful overview of the living world than simply animals and plants.

It is time to quit thinking of life science as zoology or botany, or structuring our teaching albums (manuals) this way. When we offer only two categories for living things, children miss much of the living world. While young children are not ready for lots of details, they can sort pictures of living things into three categories, the third being “Other living things.” This tells them that there are organisms that are neither plants nor animals, and it keeps the door open for further learning. Mushrooms, lichens, and kelp are examples of macroscopic organisms that fit under the “Other” heading.

I started my work to bring current science concepts and content to teachers over 20 years ago. My first conference workshop was about the Five Kingdom classification. I spent nearly a decade helping teachers move from two kingdoms to five kingdoms. Then I had to switch gears again as expanding knowledge (via DNA and RNA) of the relationships between living things led to new concepts of classification, principally the Tree of Life and phylogenetics. My book, Kingdoms of Life Connected: A Teacher’s Guide to the Tree of Life, has learning activities and resources for exploring all the branches of life and viruses, too.

The microscopic living world is more abstract and harder to observe than plants and animals, but that does not mean that children shouldn’t know about it. They can learn that microorganisms help plants grow, recycle nutrients, and make foods like yogurt and cheese possible. The disease-causing microorganisms are the ones that we experience most directly, and these get the most attention, but children need to understand the vital importance of microorganisms to all ecosystems.

The book, Tiny Creatures, by Nicola Davies and Emily Sutton (2014) is a valuable resource for introducing young children to the microscopic world. These authors have a second book (2017), Many: The Diversity of Life on Earth, which supports a more inclusive view of life. The Invisible ABCs by Rodney P. Anderson (2006) sounds like it would be for early childhood, but it looks better for beginning elementary. This publication from the American Society for Microbiology has accurate information and good images of the organisms. Its breezy style makes this abstract world more interesting.

Moving past botany and zoology also means considering more than biological classification. It means thinking about the ecosystems, environments, and interactions of life, the structures of life, and the evolutionary history of organisms. Elementary children will have a better idea of the importance of microorganisms after they read Ocean Sunlight: How Tiny Plants Feed the Seas by Molly Bang and Penny Chisholm (2012). This book uses the term “plants” for the ocean’s protists that perform photosynthesis, even though many are not on the green algae-plant lineage. More importantly, it shows children the microbial underpinnings of the ocean ecosystem.  

In elementary life science studies, there will be times to focus on the animals or the plants, but children will have a better perspective if they start with an introduction to the whole Tree of Life and learn to use this conceptual framework. As children develop their abstract thinking, they are likely to be interested in exploring all the branches of life. They will need good tools, such as magnifiers and microscopes, to help them observe the protists and prokaryotes. They also need appropriate search terms for finding resources they can read and understand.

I hope you and your children enjoy studying the greater living world.

Priscilla