Neanderthal man had the largest sized cranial cavity.

Explanation

### Step-by-Step Text Solution:

1. **Understanding Cranial Capacity**: Cranial capacity refers to the volume of the interior of the skull, which is often associated with brain size. A larger cranial capacity can indicate a larger brain, which may correlate with higher cognitive abilities.

2. **Neanderthal Man's Cranial Capacity**: Neanderthal man is noted to have a cranial capacity ranging from 1350 to 1700 cubic centimeters. This range indicates that Neanderthal man had one of the largest brain sizes among early human species.

3. **Comparison with Other Early Humans**:
- **Peking Man**: The cranial capacity of the Peking man is between 1000 to 1300 cubic centimeters, which is smaller than that of Neanderthal man.
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