In comparing Rand's view of human nature with what we find in the study of actual human beings, the astute observer can hardly fail to notice the degree to which Rand has stripped away everything she found annoying in man. In distinguishing all those elements that separated man from the animals, Rand, in effect, implicitly suggests that man is not essentially an animal. His animalistic characteristics are mere accidents. Man's essence is his "reason" and his volition. These elements supercede the natural or animalistic characteristics. Man has no "instincts" or innate predispositions, only such acquired dispositions as he imbibes from the people around him or his own thinking. Although it is unlikely that Rand would have ever (à la William Jennings Bryan) explicitly denied that man was a mammal, her philosophy, at times, seems to blissfully evade this palpable fact. Indeed, in some ways, this evasion is worse than an outright denial. Bryan, because of his belief in the myth of original sin, could at least be brought to recognize those actual characteristics which human beings share with animals. Rand, on the other hand, saw such characteristics (provided they were not merely physical) as defects acquired through evasion and lack of focus, rather than intregal aspects of a functioning animal.
We see this played out in the Objectivist view of jealousy, which is generally dismissive. Indeed, according to James Valliant, "Female jealousy, in the traditional sense, was alien to Rand." Valliant's view is entirely consisted with the Randian orthodoxy. Emotions can be entirely "rational," as long as the value premises behind the emotions are "rational." Of course, it would be the most dreadful heresy to suggest that Rand herself ever experienced an irrational emotion. In all of this, what is conspicuously missing is any sense of emotions as cues or incentives for behavior necessary for the propagation of the species; that, in other words, emotions exist, not to help create Rand's ideal men or provide incentives for enlightened self-interest, but to assist naturalistic goals which, in their absence, would lead to the extinction of the species. On naturalistic premises, the existence of the human species is not, nor could it ever be, the product of a rational decision, since prior to the existence of human beings, no rational thought existed. Therefore, if one wishes to be a naturalist (and this appears to be the case with Rand and her followers), one must accept those facts which are logically connected to the naturalist view.
Now under the naturalist view, jealousy is a very important emotion, necessary in the development and propagation of the species. As David Desteno and Piercarlo Valdesolo explain:
It's true that many people think of jealousy as a character flaw. But if we didn't feel jealous, we wouldn't have the kinds of stable relationships necessary to adequately protect and care for our offspring. It may not be a pleasant emotion, but sometimes it is a quite useful one, at least when experienced in mild doses. It can alert us to signs that our partner is being unfaithful or that someone is trying to steal him from us. It can also signal to our partners that we want to be in the relationship for the long term (otherwise it wouldn't be worth putting up a fight), and signal to us when they feel the same. [Out of Character, 90]
Regarding emotions as mere value premises, either accepted by default or chosen by a focused mind, renders it impossible to understand the natural and biological function of emotions within the human organism. Emotions are somatic markers or cues for predipositions and cognitive evalutions which promote the maintenance and continuance of the species. In their absence, we would no longer exist. While Rand might have been able to recognize the importance for emotions to survival, her inability to fully appreciate the mammalian side of human nature rendered her incapable of understanding the role of emotions in furthering the reproduction of the species.