TIME RELATIONS OF GROWTH : III. GROWTH CONSTANTS DURING THE SELF-ACCELERATING PHASE OF GROWTH

Area of Science:

• Biological Sciences
• Developmental Biology
• Growth Dynamics

Background:

• Growth curves are fundamental to understanding organismal development.
• Previous studies have proposed various models for growth rate analysis.
• Discrepancies exist in the literature regarding initial growth rates.

Purpose of the Study:

• To analyze the segmented nature of growth curves in higher animals and plants.
• To clarify the distinct phases and transition points within growth trajectories.
• To re-evaluate and present accurate initial growth rate data.

Main Methods:

• Analysis of growth curve data to identify distinct segments and transition points.
• Calculation of instantaneous growth rates at different developmental stages.
• Comparison of derived growth rates with existing literature values.

Main Results:

• Growth curves comprise two major segments, each with sub-segments exhibiting constant percentage growth rates.
• Transitions between segments are abrupt, analogous to metamorphosis.
• The initial instantaneous growth rate is significantly higher (100-200% per day) than previously reported, with human growth at two months post-conception being 8% per day.

Conclusions:

• Growth curves are characterized by a two-major-segment structure with abrupt transitional phases.
• The previously reported high initial growth rates in literature are inaccurate.
• Accurate growth rate analysis requires careful consideration of segmented curve dynamics.