Final answer:
Modern primates have differences, including those between Old World and New World monkeys, and early hominins with specific characteristics and environmental influences.
Step-by-step explanation:
Modern primates share general characteristics, but they also have differences. One main difference is between Old World and New World monkeys. Old World monkeys are native to Africa and Asia, while New World monkeys are found in Central and South America. They have different dental formulas, with Old World monkeys having 2.1.2.3 and New World monkeys having 2.1.3.3. Another key difference is seen in early hominins, who had characteristics such as bipedalism, increased brain size, and tool use. Environmental forces such as changes in climate and habitat may have contributed to these changes.