Background: From the data he collected and documented, Aristotle inferred quite a number of rules relating the life-history features of the live-bearing tetrapods (terrestrial placental mammals) that he studied. Among these correct predictions are the following. Brood size decreases with (adult) body mass, so that an elephant has fewer young (usually just one) per brood than a mouse. Lifespan increases with gestation period, and also with body mass, so that elephants live longer than mice, have a longer period of gestation, and are heavier. As a final example, fecundity decreases with lifespan, so long-lived kinds like elephants have fewer young in total than short-lived kinds like mice.

Situation: Albert is a scientist who travels the planet looking for new species to discover and analyze. While on a safari in Australia, Albert discovered two new species of live-bearing tetrapods. In the first species, species A, the adult individuals had high body mass on average. In the second species, species B, the adult individuals had low body mass on average.

Question: Which species will have smaller broods?
Answer: species A

Situation: Albert is a scientist who travels the planet looking for new species to discover and analyze. While on a safari in Australia, Albert discovered two new species of live-bearing tetrapods. In the first species, species A, the adult individuals had high body mass on average. In the second species, species B, the adult individuals had low body mass on average.

Question: Which species will have larger broods?
Answer: species B

Situation: Albert is a scientist who travels the planet looking for new species to discover and analyze. While on a safari in Australia, Albert discovered two new species of live-bearing tetrapods. In the first species, species A, the adult individuals had high body mass on average. In the second species, species B, the adult individuals had low body mass on average.

Question: Which species will have longer lifespans?
Answer: species A

Situation: Albert is a scientist who travels the planet looking for new species to discover and analyze. While on a safari in Australia, Albert discovered two new species of live-bearing tetrapods. In the first species, species A, the adult individuals had high body mass on average. In the second species, species B, the adult individuals had low body mass on average.

Question: Which species will have shorter lifespans?
Answer: species B

Situation: Albert is a scientist who travels the planet looking for new species to discover and analyze. While on a safari in Australia, Albert discovered two new species of live-bearing tetrapods. In the first species, species A, the adult individuals had high body mass on average. In the second species, species B, the adult individuals had low body mass on average.

Question: Which species will produce more offspring over their lifespans?
Answer: species B

Situation: Albert is a scientist who travels the planet looking for new species to discover and analyze. While on a safari in Australia, Albert discovered two new species of live-bearing tetrapods. In the first species, species A, the adult individuals had high body mass on average. In the second species, species B, the adult individuals had low body mass on average.

Question: Which species will produce less offspring over their lifespans?
Answer: species A

Situation: Albert is a scientist who travels the planet looking for new species to discover and analyze. While on a safari in Australia, Albert discovered two new species of live-bearing tetrapods. In the first species, species C, the females had long gestational periods. In the second species, species D, the females had short gestational periods.

Question: Which species will have longer living individuals?
Answer: species C

Situation: Albert is a scientist who travels the planet looking for new species to discover and analyze. While on a safari in Australia, Albert discovered two new species of live-bearing tetrapods. In the first species, species C, the females had long gestational periods. In the second species, species D, the females had short gestational periods.

Question: Which species will have shorter living individuals?
Answer: species D