Laughter is a complex response involving physical changes and emotional expressions.

• Laughter causes visible teeth, changes in breathing, weakness, aches, and sometimes tears.
• It is a response that involves rapid abdominal muscle contractions, altering breathing patterns.

Laughter likely evolved from non-verbal signals during social play among animals.

• Evidence of laughter-like behaviors has been observed in various species, including rats and primates.
• Laughter may have originally served as a signal of non-aggressive intent during rough-and-tumble play.

Human laughter evolved to convey a wider range of emotions and social cues.

• In humans, laughter is used not just during physical play but also to express amusement and various other emotions.
• The development of complex language and social structures in humans expanded the functions of laughter.

Laughter serves as a social signal and is an effective tool for emotional bonding.

• Laughter can be contagious and serves as an invitation to share emotions.
• It can indicate the nature of relationships and is louder in humans, possibly to reach a wider audience.

Humans can differentiate between genuine and forced laughter based on sound and brain activity.

• Observers can tell the difference between genuine and fake laughter.
• Volitional laughter involves speech-like brain networks, while spontaneous laughter uses older, more primal networks.

Laughter is not only a social tool but also has health benefits.

• Laughter releases neurotransmitters like endorphins and reduces stress hormones like cortisol.
• It is linked to better stress management and cardiovascular health.

While laughter is beneficial, it can be painful in certain conditions.

• Laughter can be harmful if one has a broken rib or similar conditions where laughter exacerbates pain.