Throughout the years we have learned a lot about how our bodies function and why they do the things they do, scientists have been VERY wrong in the past and some medical procedures have been very unsuccessful, and looking back we are all collectively like wow we were so dumb. But how do we know for sure we are correct now? Like how did we learn that the ovaries producs eggs that become fertilized by sperms and how on earth was this discovered and tested? How do we know its our thyroid that regulates hormones that effect other parts of the body?
In: Biology
Short answer? Centuries of trial and error coupled with technological advancement allowing for easier, more thorough, and more accurate testing/diagnostics.
Science improves over time. Each new theory is slightly better than the previous one it superseded. We must humbly assume that all of our scientific theories today are not 100% absolutely perfectly correct and true; but rather, that are they *closer to the truth* than they were in the past, and we can expect that will be *even closer to the truth* in the future.
In other words, science is always wrong but it gets **less wrong** over time.
Isaac Asimov wrote “People [once] thought the Earth was flat, they were wrong. When people thought the Earth was spherical, they were wrong [because the Earth has actually been proven to be closer the shape of an oblate spheroid]. But if you think that thinking the Earth is spherical is just as wrong as thinking the Earth is flat, then your view is wronger than both of them put together.”
Human bodies have been around for along time, and they have been cut open an examined. Some of those experiments were less ethical than we’d like, but the collection of medical knowledge grows over time. We are in no sense “sure we are correct now”. Thousands of medical researchers work every day on problems we do not yet understand. We’ve got centuries of work to go in medicine.
Sperm and eggs are pretty easy to figure out because it works the same way in humans as other mammals that are easier to experiment on. From the outside it’s clear from observing animal sex how the penis and vagina fit together. Sperm are plentiful, easy to collect, and pretty easy to see once you invent the microscope. Eggs are quite a bit trickier, but examining a dead female body will allow the connections between the organs to be figured out directly. The kinds of microscopic techniques used to harvest live human eggs without harming the woman took centuries to develop.
The role of the thyroid is pretty clear if it is removed, or a piece cut out and chemically analyzed. It’s a detective story, piecing many facts to get a coherent theory, but there are lots of people with random variation which can inform some studies.
The truth is we don’t “know” a lot of things with 100% certainty.
We are usually just very confident because we have disproven all of the competing theories. Eventually you are left with theories that have survived being disproven for decades, centuries or even millennia.
It was illegal for a very long time to study dead bodies, so we had to make do with what we could see on the outside. For a century or more, doctors followed a text from a physician named Galen, who was really wrong but was so respected that nobody wanted to go against the teachings.
Even when dead bodies were illegally examined, you can’t see the body’s workings in motion. Even then, we didn’t have the right diagnostic tools like a microscope until pretty recently.
With the invention of antibiotics, imaging, and sedation, it’s much easier to see the inside of a body and how it works while keeping the body alive. We are still learning things that disprove old beliefs.
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