Why Didn’t Humans Evolve to Be Like Crabs?
The other day, I was chilling at Slateport Beach, watching a bunch of little crabs scuttling around, and I pondered, why did humans end up as soft, two-legged beings instead of multi-legged, shell-toting crabs? Of all the crazy possibilities out there, how did humans land on this? I mean, these other creatures separately evolved to become crabs! Why didn’t you?
It’s one of those questions that really makes me scratch my blocky head. Evolution may be fun in your favorite monster-catching franchise, but it’s incredibly complex in real life. So let’s break it down—and don’t press B, okay?
What Is DNA and How Does It Drive Evolution?
Every living thing on Earth evolved over millions of years, adapting to new environments, resulting in new species like humans. All living things have a genome, or DNA, which contains all the information needed for an organism to develop and function. To understand evolution, we have to understand DNA!
DNA is made up of two long twisted chains linked by pairs of nucleotides. These chains can be divided into sections called genes, each serving a specific purpose, like the instructions to make your eyes blue. It’s the blueprint for life! DNA is tightly packaged into chromosomes, small enough to fit inside the cell’s nucleus, with each chromosome containing hundreds to thousands of genes. These chromosomes give your cells the instructions to make you, well, you.
How Do Mutations Lead to New Species?
When cells divide and multiply, the entire genome is replicated so that new cells contain the same information as their parent cell. But sometimes mistakes happen—nucleotides are replaced, deleted, or added. This is known as a genetic mutation, which can be thought of as an error in your body’s instruction manual.
Depending on the gene, mutations may not affect your body at all, but some can lead to diseases or even be beneficial. If you have kids, a mutated gene could be passed down. If it’s a helpful mutation, like losing a tail to move faster, your descendants may reproduce and continue passing it on until it spreads throughout the population. Over time, when the new population becomes different enough, it’s considered a new species.
These differences aren’t usually major—new species often look and act a lot like their ancestors and have nearly identical DNA. For example, human and chimp DNA is 98.8% the same. However, human DNA is vastly different from, say, crabs, which are on a totally different branch of the evolutionary tree.
Human Evolution and the Fusion of Chromosomes
The similarities between humans and great apes led biologists like Charles Darwin to suspect that you share a common ancestor, leading scientists to investigate your genetic differences. One big mystery was why great apes have an additional pair of chromosomes.
In 2005, scientists published evidence that human chromosome 2 is the result of a fusion of two chromosomes that are separate in other primates. Not only do the DNA sequences in human chromosome 2 match those of two chimpanzee chromosomes, but human chromosome 2 also has a vestigial center point and endpoints within it, showing exactly where the two chromosomes fused. Many scientists consider this example irrefutable evidence of evolution.
How Mutation and Chromosome Fusion Shape New Species
This fusion of chromosomes in humans is just one of many examples where mutations in chromosomes led to new species. By identifying these alterations in extinct and living organisms, scientists are gaining a better understanding of not only human evolution but also how all life on Earth came to be.
Ask Life Noggin: What Do You Want to Learn Next?
Your monster-catching days are over, Triangle Bob! I’m cutting you off. This evolution video has been a highly requested one for a while now, so tell me—what questions do you have about your world or mine? We’re taking questions for future episodes of Life Noggin!
Click here to subscribe to Life Noggin for more fascinating videos, or click here to watch a video with a world champ! As always, my name is Blocko, this has been Life Noggin, and don’t forget to keep on thinking!
Sources for this video:
https://news.gallup.com/poll/261680/a…
https://www.bbc.co.uk/religion/religi…
https://www.genome.gov/genetics-gloss…
https://www.nature.com/scitable/topic…
https://www.cancer.gov/publications/d…
https://medlineplus.gov/genetics/unde…
https://www.ncbi.nlm.nih.gov/books/NB…
https://my.clevelandclinic.org/health…
https://my.clevelandclinic.org/health…
https://www.nature.com/articles/s4158…
https://www.discoverwildlife.com/anim…
https://medlineplus.gov/genetics/unde…
https://www.amnh.org/exhibitions/perm…
https://www.pbs.org/wgbh/evolution/li…
https://rmpbs.pbslearningmedia.org/re…
https://genomebiology.biomedcentral.c…
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