Final answer:
Sexual dimorphism involves physical differences between males and females of a species. In early hominids, such as Homo ergaster, reduced sexual dimorphism may have indicated less male competition and a monogamous mating system, posing advantages for offspring care and survival. However, these relationships between physical traits and behavior are complex and not uniformly applicable.
Step-by-step explanation:
What is Sexual Dimorphism?
Sexual dimorphism refers to the differences in appearance between males and females of a species beyond their sexual organs. These differences can include size, coloration, the presence of ornaments such as the peacock's tail, and may arise due to variances in reproductive success among individuals. For instance, males may be selected for attributes that enhance their mating success, such as greater size or more striking visual traits.
Advantages of Sexual Dimorphism in Early Hominids
In early hominids, such as Ardipithecus ramidus and Homo ergaster, evidence suggests a shift towards reduced sexual dimorphism compared to earlier ancestors. This lesser degree of size difference between the sexes implied less male-male competition and potentially a move towards a more monogamous mating system. This could lead to greater parental investment in offspring, potentially indicating a more cooperative social structure and better offspring survival rates. The evolution of reduced sexual dimorphism in early hominids was therefore likely advantageous for enhancing the survival and development of their young.
It is important to note that although sexual dimorphism can suggest certain mating strategies or social structures, researchers like anthropologist Adrienne Zihlman warn against overly simplistic correlations between physical characteristics and behavior, as these can vary widely even within a species.