A study found that men with low testosteron levels have wider smiles. Among women, this relationship largely does not exist.

"In a study of possible links between testosterone and dominance, 119 men and 114 women provided saliva samples for testosterone assay and posed smiling and not smiling for portrait photographs. Expert judges viewing the photographs found smaller smiles among high than low testosterone men, with less zygomatic major (raising the corners of the mouth) and orbicularis oculi (raising the cheeks and crinkling around the corners of the eyes) muscle activity. Naive judges viewing individual photographs gave higher potency ratings to smiling high testosterone men than smiling low testosterone men. Naive judges viewing photographs grouped into high and low testosterone sets gave higher potency and lower goodness ratings to high than to low testosterone men, regardless of whether they were smiling. Among women, judges found only slight relationships between testosterone and facial appearance. The pattern among men of less smiling with higher testosterone levels fits with research linking testosterone to face-to-face dominance."

https://link.springer.com/article/10.1023/A:1024947801843

So, probably beta males have wider smiles when talking to women? What do you think from your experience?