![]() ![]() Two or more species originate from ancestral species due to speciation (or cladogenetic) events – when a line splits into two. Figure 3: A diagram (also known as cladogram) that accurately depicts evolution. In figure 3, these events are represented by the points at which one line “bifurcates” into two lines. Cladogenetic events are the moments in time during which one species “splits” into two species – these events are also known as speciation events. Unlike figure 2, a cladogram captures the most important (and ongoing!) aspect of the evolutionary process: “branching,” or what biologists refer to as cladogenesis. Biologists have given diagrams like this a fancy name: cladogram. Erase this simplistic cartoon from your mind, Mr. For an evolutionary biologist living in the 21st century like me, this is as misguided as asking why people on the other side of the world do not fall into the void of space.Įvolution is not a linear process that starts with more “primitive” looking organisms we can observe today, and ends in mankind (as shown in Fig. This question reveals a fundamental misunderstanding of the natural phenomenon of evolution. Why? Let me use the smaller scale generational parallel to rephrase his tweet, even if I risk jumping the gun on my own argument: “If I am grandfather Allen’s grandson, how come I have Allen cousins?”. Allen’s question could be a publicity stunt, or maybe he is just a provocateur, but many of the 50,000 “likes” his tweet has at the moment are probably genuine. According to the cartoon, evolution is strictly linear, with more “primitive” creatures evolving into “less primitive” ones. Figure 2: A (terrible) cartoon representing how many people imagine evolution happens. The small-scale equivalent (if you “zoomed in”) would be the linear genealogical chain from grandparent to grandchild. Over many generations, this process culminated in us (Fig. ![]() Allen calls an “ape” – had a baby that looked less “ape-ish” and more “human-ish”. Allen most likely imagines when he thinks about evolution: At some point in the past, this monkey-like creature with long limbs that you can see at the zoo – what Mr. I am talking about tweets like this one (Fig. More often, however, I read tweets that cause anxiety and make me frown at my computer screen with the countenance of a distraught fish. Chimpanzees and all other nonhuman primates have only the working version in other words, they’re on the powerful, “sprinter” end of the spectrum.When I am on Twitter, every now and then a witty or funny tweet catches my attention. People with two working versions of this gene are overrepresented among elite sprinters while those with the nonworking version are overrepresented among endurance runners. (Puny jaws have marked our lineage for as least 2 million years.) Many people have also lost another muscle-related gene called ACTN3. One gene, for example, called MYH16, contributes to the development of large jaw muscles in other apes. In the past few years, geneticists have identified the loci for some of these anatomical differences. A chimpanzee’s skeletal muscle has longer fibers than the human equivalent and can generate twice the work output over a wider range of motion. But a more important factor seems to be the structure of the muscles themselves. How did we get to be the weaklings of the primate order? Our overall body architecture makes a difference: Even though chimpanzees weigh less than humans, more of their mass is concentrated in their powerful arms. But it is a fact that chimpanzees and other apes are stronger than humans. So the figures quoted by primate experts are a little exaggerated. So he packed up a device used to measure pull strength, called a dynamometer, and set out for the Bronx Zoo. Poe’s story of the scalp-pulling orangutan struck Bauman as being “ grotesquely impossible.” In 1923, he noted that every expert in the field believed apes were vastly stronger than humans-yet none had ever tried to prove it. The suspicious claim seems to have originated in a flapper-era study conducted by a biologist named John Bauman. It’s just the sort of factoid the zoo staff might tell you to keep you from knocking on the glass. If the “five to eight times” figure were true, that would make a large chimpanzee capable of bench-pressing 1 ton. Consider that a large human can bench-press 250 pounds. But it sounds extreme to suggest that humans are only an eighth as strong as chimpanzees. A chimp on four legs can easily outrun a world-class human sprinter. Their climbing lifestyle accentuates the need for arm strength. ![]() Pulled scalps? Unstuck wagons? No doubt, chimpanzees are different from us. ![]()
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