JSFiddle - React, Tailwind, and code Playground

HTML

<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<div id="australopithecus">
  <div id="homo-herectus">
    <div id="homo-sapiens"></div>
  </div>
</div>

JavaScript

let parent = $('#australopithecus #homo-sapiens').length;
let child = $('#homo-sapiens #homo-herectus').length;

if (parent === 1) {
	console.log('homo-herectus предок');
} else {
	console.log('homo-herectus потомок');
}

if (child === 1) {
	console.log('homo-sapiens предок');
} else {
	console.log('homo-sapiens потомок');
}