Evidence of Evolution 10/27

All living things evolve from one common ancestor. But what evidence do we have of this? How do we know that evolution has actually occurred?

There are several ways to know how evolution has occurred.

- Morphology
- Embryology and development
- The fossil record

Morphology

Morphology is the differences and similarities between living things. ‘Morpho’ is the Latin word for ‘shape’, so morphology (also called comparative anatomy), is the shape of bone structures and their similarities and differences.




This image shows the arm structures of a frog, a lizard, a bird, a cat, a whale, a bat and a human. Based on the similarities and differences, or morphology, in these bone structures, which animal(s) is the human most closely related to here?

Embryology and development

Embryology and development is how things develop before and after birth. While the fetus of a human is still developing, it may look similar to that of a monkey. However, after it is born, more differences begin to appear.




In this image, the pictures colored in blue look the same. The pictures that are yellow, pink or green look different from the blue ones and all the others. You are able to see the similarities in the developing fetuses of a human, a monkey, a pig, a chicken and a salamander. Based on this, which animal do you think is most closely related to the human in this image?

The fossil record

The fossil record is the observations seen of organisms that existed in the past. At this link, we are shown evidence and what it tells us. We can see that the fossil of the curled up trilobite may be trying to protect itself by curling up, similar to today’s pill bugs. Fossils of many of the same organism in some place helps us determine that these organisms may have traveled in packs. Seeing the same fossil on two separate continents may lead to inferences about continental drift. For more information of the fossil record, go here.

S&EP: SP2 Developing and using models

This week, we used to models in the images above to look deeper into the evidence of evolution. The first model had us use colored pencils to color the bones in each organism’s arm structure. This helped up see the bone placement of humans and other organisms. In the second image, we examined the developing fetuses of organisms and looked into the similarities before and after birth. These models helped me see and understand the evidence for evolution. Seeing the similarities between organisms helped support the theory that all living organisms evolved form one common ancestor.

XCC: Patterns
Patterns between organisms help us see the similarities and differences between them. In the first image of the similar bone structures, we can see the organisms more closely related to humans because of their similarities. When we study things like the fossil record, we can connect patterns to study extinct creatures and organisms that may have evolved into modern-day organisms. Trilobites from millions of years ago shared traits with pill bugs from today. We can make predictions that organisms from millions of years ago may have evolved into some of the most common creatures today.

Natural Selection 10/21

Darwin's finches by Wikimedia Commons

The theory of evolution was started up by Charles Darwin, the scientist who established that all living things come from one common ancestor. He introduced the theory that evolution results from the process natural selection.

Natural Selection

Natural selection is one of the forces that drives evolution. Organisms that are well adapted to their environment will generally survive long enough to pass on their genes to their offspring. Organisms that have genes that are harmful to them are unable to survive long enough to pass on genes. As a result, no offspring will be produced. The harmful genes/traits are unable to be passed on and will die off within that population/species.

The peppered moth is a common moth in Europe, Asia and North America. The moths has two appearances, the light, speckled morph and the dark morph. These two morphs help it camouflage from its biggest predator: the bird.

When the moths were light, they would rest on woodland lichens, camouflaging in the flowers and staying hidden form the birds that preyed upon it. When the industrial revolution came, soot killed the lichens and turned the trees black. The moths were no longer able to camouflage on the dark trees. They were killed and eaten. Over time, natural selection killed off the light genes, and dark moths replaced the lighter ones. In 1956, the Clean Air Act removed soot from the nation’s sky, and the trees began to turn light. Once again, the moths were exposed, and once again, they evolved to stay hidden.

As could be seen from the moths, the more favorable traits are passed on, while the harmful or less desirable traits are lost.

Darwin’s finches

Charles Darwin came up with the theory of evolution. He visited a series of islands to study organisms and how they lived. There, he noticed finches, a type of bird.

Darwin noticed that the birds from the different islands looked similar and were the same species (finches), but they weren’t exactly the same. A finch on one island had a deeper beak than a finch on the other island. Darwin wondered why that was and came up with the theory of evolution.

The finches from the different islands were perfectly suited to the resources of their island. Once island had seeds that had hard shells, so the finches developed sharp beaks to crack the shells. Other finches from another island didn’t because their seeds are easy to eat as they are. If you put a finch from the easy seed island onto the tough shell seed island, it would either die or starvation or evolve to develop a beak to eat the seeds.

Natural selection helped the finches evolve to develop the favorable traits that would help them survive on their own respective islands and resources.

S&EP: SP2 Using Models

GoFormative used simulations that helped me study natural selection. Using this simulation on the Explorelearning Gizmos, I was able to pretend to be a bird and practice trying to catch peppered moths on light and dark trees. This simulation and the graphs/charts helped me understand how the camouflaged moths were able to stay hidden from birds more than the exposed ones. This model was very helpful because I was able to see the graphs that were made based on the number of moths I ‘caught’ during the simulation.

XCC: Structure and Function

Natural selection helped the finches on the islands evolve into a structure that was better suited to their environment. Each of the finches had a different structure based on their island. A finch on an island that had tougher seeds would have a sharper beak in their structure. A finch on an island that had lots of insects would have a more delicate and longer beak to pull bugs out of holes. The finches don’t need to crack thick shells, so their delicate beaks would not be able to open the seeds. The finches with the sharper beaks wouldn’t be able to reach bugs in the holes because their beaks would not be long or thin enough. The way the finches are built directly affects how they survive and function. If the finch is not built to crack seeds, it will die if it is placed on the seedy island. If the finch has a wider and sharper beak than another finch, it is less likely to survive on a buggy island than a finch with a thinner beak. If the finch is not built for the environment, it will not be able to survive.

Evolution 10/12

Human Evolution Scheme by Wikipedia

Evolution is any change in the gene pool over time. Cutting your hair is not evolution because it isn’t happening over time, and it’s not a heritable trait. Evolution happens over multiple generations, and the change is hereditary, meaning that you can pass it on to your offspring.

There are five things that influence evolution, and they can be remembered by the fingers on you hand.

The pinkie finger is population shrinking, also called genetic drift. Genetic drift is the term scientists use to describe shrinking or increasing of a specific gene or trait in a population. If five people were stranded on a desert island, and two of them had red hair, some of the offspring would have red hair, but, since the red hair population wasn’t very large to begin with, the red hair trait might die off in the next few generations.

The ring finger is mating with specific traits. This is an obvious way that genes would be passed on.

The middle finger is mutations. Mutations change the DNA and genes of an organism randomly, and the mutation can be beneficial, negative or neutral to that organism. If a cat was born with floppy ears and neither of its parents had floppy ears, that would be a neutral mutation, meaning that the ears neither benefit nor harm the cat.

Gene flow is the pointer finger. Gene flow is when genes move from one population to another. In that population, those genes that were carried to it didn’t previously exist. If a white dog ran into a population of black dogs, their offspring would be white and black.

The thumb is natural selection. Natural selection is when there are two traits in the gene pool. One of the genes is more beneficial to a certain species than the other. The more common trait is passed on, and the other trait dies off. Natural selection eliminates certain traits in the gene pool to cause change in heritable traits. If green and blue birds lived together in a population, and the blue birds were eaten more often, there would be less blue birds to reproduce. The blue bird gene would soon die off, and only green birds remain in the population.

S&EP: SP3: Planning and Carrying out Investigations

We collected data in a mutations lab simulation. Each group of four received 25 M&M’s in a cup. We first began with counting the number of M&M’s in each color and wrote the numbers down. We had to find out the percentage of the total population that color was. Each person at the table had to pick five out of the cup randomly. The first person went, and then we recounted and recalculated, adding in five red hots so the total population stayed the same. We repeated this, each time dumping out the M&M’s and matching them up in pairs of the corresponding color. If there was an extra red and yellow, we would pair them up and set them to the side. If the pairs had two of the same color, we would add another M&M of that color to the cup. If the pair was of red hots, we would add a red hot. If we had a pair like the red and yellow pair, we chose one of the colors to add. This way, colors could ‘die off’ within the population. In our group, the brown candies dominated and the red ones died off. This lab helped us see the way that evolution worked with mutations.

XCC: Stability and Change

IN NATURE, SOME THINGS STAY THE SAME AND SOME THINGS CHANGE. CHANGES CAN BE FAST OR SLOW.

Evolution is the perfect example of how slow changes occur in nature. Change is only evolution if it occurs over several generations, meaning that the changes are not immediate. The five fingers can cause evolution. Evolution can occur because of a mutation that causes the organism to change, like a puppy with extra furry ears even though its parents did not have extra fluffy ears. The puppy will pass on the fluffy ear trait to its descendants, and the descendents will pass it on, and soon the puppy population will have lots of puppies will fluffy ears. As long as the changes in the organism are hereditary (able to be passed on in genes to offspring) and last several generations, the changes are evolution.

WAC | We are not in a sixth mass extinction | 10/5/18

Despite what scientists are saying and thinking, we are not in a sixth mass extinction. Though signs may point that direction, we aren’t there yet. It is possible that in the very near future we will enter a mass extinction, but we haven’t reached that point. Five mass extinctions have been recorded in Earth’s history, each wiping out 70% of life on the planet or more. However, as stated by the 22nd paragraph in AEON’s article We are not edging up to a mass extinction by Stewart Brand, “There were soon many more species alive after each catastrophe than there were before it.” Even if we were in the midst of a sixth mass extinction, it would take decades, maybe even centuries to the see the results, and if anything was still alive, it would find a way to adapt to the new environment, or it would die. Eric Worrall states in his article Paleo Expert: Earth is Not in the Midst of a Sixth Mass Extinction that “...this is because by the time a mass extinction starts, the world would already be over.” It would take a long time to see if we were in a mass extinction, and by the time we had entered it, everything would already be gone. As has been noted, scientists are saying that a mass extinction might be coming in the very near future, but it won’t begin for a while. Still, scientists are not denying that humans are the reason this might happen. 

Even though some might argue that climate change is the reason more and more species are going extinct, there are quite a few that are actually adapting to the circumstances around them and finding new ways to survive. It might not be easy, but it is possible. Stewart Brand’s AEON article brings up a good point in saying, “Move, adapt or die. When organisms challenged by climate change respond by adapting, they evolve. When they move, they often encounter distant cousins and hybridise with them, sometimes evolving new species. When they die, they leave a niche open for other species to migrate or adapt into, and a warming climate tends to open the way for more species rather than fewer.” Take the Galapagos islands for example. They started out as nothing but a barren wasteland of volcanic rock and ash, and when organisms moved to them or were swept out to sea and were stranded, they either had no way to get back to where they were or they didn’t want to. Lizards that ate leaves were moved to an arid island free of vegetation and had to evolve to dive deep and reach the nearest plant: seaweed. Over hundreds of years, the lizards that used to be living in trees were diving into the ocean to reach seaweed to survive. Animals and other organisms are able to adapt to their circumstances and help each other, no matter what may happen. Climate change could be affecting animals and organisms, like marine life or organisms that inhabit rainforests. When we destroy habitats for our own gain, that can deplete entire species that were once proliferating. As mentioned earlier, most organisms can adapt, but there are some that are unable to and die off completely. Just because some species are going extinct doesn’t mean that we’re in the midst of a mass extinction, but it does mean that if we keep it up, we could be. 

Even though another mass extinction event seems to be coming, we still won’t be around to see it. If another does occur because of human activity, it will happen within the next few decades or even centuries. That doesn’t seem so close, but most mass extinctions in the past took hundred to thousands of years to physically begin destroying the world. 

“Nothing we have done to the climate or the world in general comes anywhere close to the unimaginable circumstances of previous mass extinctions.”, says Eric Worrall in his article Paleo Expert: Earth is Not in the Midst of a Sixth Mass Extinction. “Erwin does not rule out the possibility we might somehow trigger a mass extinction in the future. But killing off a few photogenic species simply doesn’t qualify.” Being the cause of several extinctions isn’t wonderful, but it also isn’t triggering the end of the world. Although some people may think that the extinction will wipe out all life and humanity within the next decade or so, a devastating event is several centuries away. AEON states that “Many now assume that we are in the midst of a human-caused ‘Sixth Mass Extinction’ to rival the one that killed off the dinosaurs 66 million years ago. But we’re not. The five historic mass extinctions eliminated 70 per cent or more of all species in a relatively short time. That is not going on now. ‘If all currently threatened species were to go extinct in a few centuries and that rate continued,’ began a recent Nature magazine introduction to a survey of wildlife losses, ‘the sixth mass extinction could come in a couple of centuries or a few millennia.’” Just because seem like they’re looming closer doesn’t mean they actually are, and our generation isn’t in any danger from any mass extinctions any time soon.

Some people might argue that we are in a sixth mass extinction. Some scientists believe the same things, but there is no solid proof that we are. Still, there are people who are arguing for this position, and there are many reasons why. In CNN’s article Sixth mass extinction: The era of 'biological annihilation' by John D. Sutter, it states that “‘We've got this stuff going on that we can't really see because we're not constantly counting numbers of individuals,’ he said. ‘But when you realize that we've wiped out 50% of the Earth's wildlife in the last 40 years, it doesn't take complicated math to figure out that, if we keep cutting by half every 40 years, pretty soon there's going to be nothing left.’” More people argue for this because studies show that species are depleting faster and faster. “In a 2015 study, biologist Paul Ehrlich and his team argued Earth is in an era of mass extinction rivaling the one that killed the dinosaurs. They estimated Earth is losing mammal species 20 to 100 times the rate of past such extinctions and that the rate is only expected to speed up.”, says Newsy’s article Scientists Can’t agree if we are really in a mass extinction by Sarah Schlieder. However, people have been trying to help the environment by recycling, using eco-friendly cars and solar panels to power things instead of using pollutants. This rate of extinction has probably lowered since the time this study took place, three years ago.This argument is not enough to change the fact that we aren’t in a mass extinction. Eric Worrall’s Paleo Expert: Earth is Not in the Midst of a Sixth Mass Extinction article just about sums it up, saying, “Picture previous mass extinctions; the sky darkened for months, maybe years by gigantic impacts or vast volcanic eruptions which lasted for thousands, even millions of years; Poisonous fumes spreading across the entire world, choking the life out of entire continents; A handful of animals and plants somehow scrounging warmth and food from an almost lifeless wasteland.Compare this nightmarish hellscape to the slight wobble we may have helped introduce to global temperatures, a wobble so small it cannot be reliably differentiated from previous natural wobbles which occurred in the last few centuries.” What we are doing may not be good, but it isn’t ending the world either. 

Even though many amazing species are going extinct faster and faster, that doesn’t necessarily mean that a mass extinction is in the near future. Mass extinctions wiped out over 70% of all life on Earth, and the eradication of a few species, beloved as they are, doesn’t really count. 

Newsy’s article Scientists Can’t agree if we are really in a mass extinction says, “Stewart Brand, president of the Long Now Foundation, says current rates don't signal a mass extinction because the past five wiped out at least 70 percent of all species in a relatively short time. He says current rates are too slow for us to be in the middle of one.” This means that, even though the extinction of several species is bad, it isn’t a massive destructive event that’s going to destroy the world.Eric Worrall’s Paleo Expert: Earth is Not in the Midst of a Sixth Mass Extinction article goes on by saying, “‘Many of those making facile comparisons between the current situation and past mass extinctions don’t have a clue about the difference in the nature of the data, much less how truly awful the mass extinctions recorded in the marine fossil record actually were,’ he wrote me in an email. ‘It is absolutely critical to recognize that I am NOT claiming that humans haven’t done great damage to marine and terrestrial [ecosystems], nor that many extinctions have not occurred and more will certainly occur in the near future. But I do think that as scientists we have a responsibility to be accurate about such comparisons.’” 

People may think that extinctions are coming to destroy the world, but they need to make sure that they’re getting accurate information. Some people only glance at a headline instead of reading the article below it, which may have a very different perspective than a single line of text. All in all, some people are assuming things that aren’t true or isn’t the proper information. 

The Earth is not in a sixth mass extinction, no matter what things seem like. They might be coming up soon, sometime within the next few centuries, but we’ll all be gone, so there’s nothing really to worry about. Even though several beloved species, like the African elephant and the Black Rhino, are going extinct, that doesn’t necessarily mean that everything is going to die. Like the Galapagos example, organisms are fully able to adapt to their new surroundings and even evolve into an entirely different organism if they need to to survive barren wasteland, underground, in the forest or in a desert. People that just scan for headlines don’t know the full picture. If you don’t read the articles below, you’ll never really know some ideas and information that could change your entire perspective. Even though headlines may read, ‘BLACK RHINO, NEARING EXTINCTION’, that doesn’t mean that we’re all in danger. Next time someone tells you something that may seem questionable, check to make sure that you can see the full picture and both sides of the argument. Once again, even though many people argue against it, we are not in a mass extinction.