<p>One reason that an insect can walk on walls while a human cannot is that the mass of its tiny body is far lower than humans.</p>
<p>Should the underlined portion be changed into "far lower than that of a human"?</p>
<p>One more question:
In his new book, Quest for Adventure, the renowned British mountaineer Chris Bonington examines the past century’s most remarkable expeditions, profiling such explorers including Neil Armstrong, Thor Heyerdahl, and Maurice Herzog.</p>
<p>Should the underlined portion be changed into "as"?</p>