We need to count selections of 4 books that include 2 or more biographies (from 4 biographies and 6 novels).

Case 1 — Exactly 2 biographies + 2 novels:
$\binom{4}{2} \times \binom{6}{2} = 6 \times 15 = 90$

Case 2 — Exactly 3 biographies + 1 novel:
$\binom{4}{3} \times \binom{6}{1} = 4 \times 6 = 24$

Case 3 — Exactly 4 biographies + 0 novels:
$\binom{4}{4} \times \binom{6}{0} = 1 \times 1 = 1$

Total $= 90 + 24 + 1 = \mathbf{115}$.