Over the past 10,000 years, we "modern humans" have learned to live together in social groups and communities. Rules and codes of conduct for finding a mate and producing offspring were developed to minimize overt sexual competition. Violation of the mating rules -- and even minor deviations from the rules in some cultures -- often brings severe criticism and consequences. Violators soon learn there is a price to pay for deviation from the local rules about revealing their natural sexual drives and seeking a mate in unconventional ways.
In spite of all the social pressure to hide and suppress our natural sexual urges, our sexual desires are still often revealed in our unconscious body language.
Many people will argue that we humans today have a higher purpose than getting sex. However, research has found that much of our body language still reveals an unconscious desire to get naked and have some sexual fun. There is abundant research indicating that body language is still unconsciously geared to finding a mate and get sex. Interestingly, this drive to get sex and reproduce is handled differently in men and women. Generally, single men are looking for immediate sex. Single women are more often looking for a relationship first, and then sex may happen afterwards.