Although Charles Darwin's writings and ideas have proven controversial, I think it's an interesting topic to consider that he was just like everyone else in the sense that he was married, had a family, and found his baby to be the most magnificently interesting human in the world! Below you'll find Charles Darwin's observations of his own baby in an article titled:
A Biographical Sketch of an Infant
"During the first seven days various reflex actions, namely sneezing, hiccuping, yawning , stretching and of course sucking and screaming were well performed by my infant. On the seventh day, I touched the naked sole of his foot with a bit of paper, and he jerked it away, curling at the same time his toes, like a much older child when tickled. The perfection of these reflex movements shows that the extreme imperfection of the voluntary ones is not due to the state of the muscles or of the coordinating centers, but to that of the seat of the will. At this time, though so early, it seemed clear to me that a warm soft hand applied to his face excited a wish to suck. This
must be considered as a reflex or an instinctive action, for it is impossible to believe that experience and association with the touch of his mother's breast could so soon have come into play. during the first fortnight, he often started on hearing any sudden sound, and blinked his eyes.. At the age of 32 days, he perceived his mother's bosom when three or four inches from it, as was shown by the protrusion of his lips and his eyes becoming fixed; but I much doubt whether this had any connection with vision; he certainly had not touched the bosom. Whether he was guided through smell or the sensation of warmth or through association with the position in which he was held, I do not at all know.
Anger. it was difficult to decide at how early an age anger was felt; on his eighth day he frowned and wrinkled the skin round his eyes before a crying fit, but this may have been due to pain or distress, and not to anger. When about ten weeks old, he was given some rather cold milk and he kept a slight frown on his forehead all the time that he was sucking, so that he looked like a grown-up person made cross from being compelled to do something which he did not like. When nearly four months old, and perhaps much earlier, there could be no doubt, from the manner in which the blood rushed into his whole face and scalp, that he easily got into a violent passion...
Fear. This feeling probably is one of the earliest which is experienced by infants as shown by their starting at any sudden sound when only a few weeks old, followed by crying. [...When he was 4 1/2 months old] I one day made a loud snoring noise which I had never done before; he instantly looked grave and then burst out crying. Two or three days afterwards, I made through forgetfulness the same noise with the same result. May we not suspect that the vague but very real fears of children, which are quited independent of experience, are the inherited effects of real dangers and abject superstitions during ancient savage times?...
Pleasurable Sensations. It may be presumed that infants feel pleasure while sucking and the expression of their swimming eyes seems to show that this is the case. This infant smiled when 45 days, a second infant when 46 days; and these were true smiles, indicative of pleasure, for their eyes brightened and eyelids slightly closed. The smiles arose chiefly when looking at their mother, and were therefore probably of mental origin.
Affection. This probably arose very early in life, if we may judge by his smiling at those who had charge of him when under two months old; though I had no distinct evidence of is distinguishing and recognising anyone, until he was nearly four months old. When nearly five months old, he plainly showed his wish to go to his nurse. With respect to the allied feeling of sympathy, this was clearly shown at 6 months and 11 days by his melancholy face, with the corners of his mouth well depressed, when his nurse pretended to cry. Jealously was plainly exhibited when I fondled a large doll and when I weighed his infant sister, he being 152 1/2 months old.
Association of ideas, Reason, etc. When four and a half months old, he repeatedly smiled at my image and his own in a mirror, and no doubt mistook them for real objects; but he showed a sense in being evidently surprised at my voice coming from behind him. Like all infants he much enjoyed thus looking at himself, and in less than two months perfectly understood that it was an image; for if I made quite silently an odd grimace, he would suddenly turn round to look at me.... When five months old, associated ideas arising independently of any instruction became fixed in his mind; thus as soon as his hat and cloak were put on, he was very cross if he was not immediately taken out of doors...
Means of Communication. The noise of crying... is of course uttered in an instinctive manner, but serves to show that there is suffering. After some time the sound differs according to the cause, such as hunger or pain... when 46 days old, he first made little noises without any meaning to please himself, and these soon became varied. An incipient laugh was observed on the 113th day. when five and half months old, he uttered and articulated sound "da" but without any meaning attached to it. when a little over a year old, he used gestures to explain his wishes... At exactly the age of a year, he made the great step of inventing a word for food, namely, mum, but what led him to it I did not discover. Before he was a year old, he understood intonations and gestures, as well as several words and short sentences. He understood one word, namely, his nurse's name, exactly five months before he invented his first mum; and this is what might have been expected..."
