A brief (and admittedly overly simplistic) account of human evolution posits that roughly 6-million years ago a group of apes—the ancestors of what would become humans—stood up on the African plains to see over the tall grass. This newfound posture provided them with the opportunity to use their two newly freed limbs (no longer necessary for ambling about on all fours) to carry and use tools. More complex tools precipitated more complex brain activity and our ancestors’ brains grew in size and function, which in turn inspired more complex tools, which then brought about more complex brain activity, and so the cycle continued.
While there are many benefits to an ever-increasing brain size, such growth is not without its detriments. A large human skull becomes more difficult to fit through the birth canal, and so human birth became more and more of an ordeal as the brain case continued to increase in size. Eventually, human skulls became so large that both the mother and infant died in birth unless the child was born earlier in the gestation cycle—this is the reason human infants are rather helpless at birth, lacking motor skills and functional sensory organs, while other mammals (including other apes) are able to walk, climb, swim, or fly only a short time after birth. In that sense, we are all premature.
These machinations of evolution rendered human childbirth one of the most painful and damaging necessities of biology in the animal kingdom, and made human motherhood much more exacting as the infant is almost completely incapacitated at birth.
All this is to say, that human mothers have, through their reproductive cycles and gravidity, borne the brunt of the burdens that have allowed for humans’ increased capacity for reason and thought and made life, as we know it, possible. So I guess what I’m saying is, ‘Thanks Mom!’