Mac Dictionary defines it as:
an individual animal, plant, piece of a mineral, etc., used as an example of its species or type for scientific study or display.
• an example of something such as a product or piece of work, regarded as typical of its class or group.
• a sample for medical testing, esp. of urine.
• informal used to refer humorously to a person or animal : in her he found himself confronted by a sorrier specimen than himself.
So technically we humans are specimens?