in the year 2000
Crabs are just like people (OK, maybe not) in that they have glands that produce hormones, and these hormones then travel around their bodies affecting physiology and behavior.
Think of your pituitary gland and all the amazing things it's done for you (and for that guy from The Relic). Crabs have something similar: the X-organ sinus gland (XO-SG; see fancy drawing). Just as the pituitary gland controls the function of other endocrine glands, the XO-SG controls (by inhibiting) the function of the mandibular organs (MO) and Y-organs in crabs. And just as the pituitary gland produces follicle-stimulating hormone (FSH) to stimulate the ovaries and testes of humans, the MO produces methyl farnesoate (MF) to stimulate gonad development in crabs!
See, we're so similar!!