After baby teeth go, secondary teeth grow, is there a scientific reason why they are just 2 sets not more?
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$\begingroup$ I found this question biology.stackexchange.com/q/27547/15122 which answers the history section of my question $\endgroup$– Amr ElgarhyCommented Apr 1, 2015 at 13:09
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2$\begingroup$ Which of Tinbergen's four why-questions are you asking? See e.g. sciencegamed.co.uk/science/2013/mar/…. $\endgroup$– DaanCommented Apr 1, 2015 at 16:10
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1$\begingroup$ This not a duplicate. The first part of the question is why humans usually only have two sets of teeth. $\endgroup$– canadianerCommented Apr 1, 2015 at 21:25
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1 Answer
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Humans are diphyodont animals, which means we are having two sets of teeth cycles, on contrast, the polyphyodont animals which are having multiple tooth cycles. The first deciduous teeth(milk teeth,baby teeth or primary teeth) then followed by the permanent teeth. Milk teeth develop from the embryonic stage and continue to develop for 6-7 years and gradually erupts forming the permanent teeth. The permanent teeth is developed and it pushes the milk teeth from the bottom which result in the shredding of milk teeth.
Most of these polyphyodont animals uses their teeth for more severe purposes like grabbing and slashing. Due to these massive work load, their tooth are considered as their main advantage for survival. Also their tooth are subjected to heavy flaws while they grab or slash, so having multiple tooth cycles help them ensure healthy teeth all over their life time. On the other hand considering the diphyodonts, their tooth have been using for chewing and grinding and they will having low flaws compared to the others. So from the evolutionary standpoint increasing the number of tooth cycles are not so economic for them. Reference
answered Apr 2, 2015 at 4:52
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$\begingroup$ there are plenty of polydont grinders and chewers. polydont is the default, mammals are weird for losing it. $\endgroup$– JohnCommented Aug 28, 2019 at 13:53