Many times people will refer facetiously to male nipples as stark evidence of vestigiality. Indeed, what use do men have of nipples if they cannot breastfeed? Well....not so fast. Did you know that men can, indeed, breastfeed? Men in fact possess mammary glands, albeit much smaller ones, so that if the mother passes away or is not in the child's life for any period of time, the father can nurse the child in a pinch. If you are still unconvinced of this, then just look here to watch a father give suckle to his child. What's going on here?
Well, what's going on is that it is becoming increasingly apparent that vestigiality is no longer a tenable idea, at least among us homo sapiens. Take the appendix, for example. Long thought to be a vestigial organ, we now know that it plays a very important role in our bodily health by generating and preserving probiotics. The same goes for the incredibly annoying wisdom teeth. It turns out that, again, rather than being a mere evolutionary leftover, wisdom teeth assist the other molars in grinding and tearing movements as well as help to stabilize the jaw.
But that's not all! What about the pesky coccyx? What on earth do we need that for now that we don't have a tail anymore? Well again, we find that this putatively vestigial organ serves several important functions. To wit:
"In the human body, the coccyx serves a variety of important functions, including as an attachment site for various muscles, tendons, and ligaments. Physicians and patients should remember the importance of these attachments when considering coccygectomy).
"Muscles inserting on the anterior coccyx include the levator ani, which is sometimes considered as several separate muscle parts, including the coccygeus, iliococcygeus, and pubococcygeus muscles. This important muscle group supports the pelvic floor (preventing inferior sagging of the intrapelvic contents) and plays a role in maintaining fecal continence. A midline component is the anococcygeal raphe, whereby the coccyx supports the position of the anus.1 Muscles originating on the posterior coccyx include the gluteus maximus, which is the largest of the gluteal (buttock) muscles and which functions to extend the thigh during ambulation."
In short, the coccyx serves as an attachment site for various muscles, nerves, ligaments, etc. and that without it we risk weakening our pelvic floor or even incontinence!
We now come to the tonsils. Tonsils are an important part of the immune system and their function is to trap germs and other harmful bacteria which we breathe in. The tonsils secrete antibodies which kill said germs thereby preventing infection. Again, it isn't looking good for vestigiality.
This is all without mentioning the fact that supposed "junk DNA"-another vestige-isn't junk at all! Unfortunately, many (not all, of course) biologists take any criticism of evolutionary theory as an affront to science and treat the critics as if they are all Young Earth Creationists with a theological ax to grind. This is disingenuous and it needs to stop. As we see here, a key feature of evolutionary theory-vestigiality-has been disproven. Any theory which cannot adapt to the times runs the risk of ossifying into another ideology, and the moment it does that it ceases to be scientific. Furthermore, the notion that only fundamentalist religionists are the ones criticizing evolutionary theory is also wrong, as two recent scholarly works (this one and this one) show, having been written by atheists. The evidence is there in black and white, and we can only hope that the more stubborn biologists among us will listen to reason.