what will happen if there are only human beings living on the earth without any other animals

If Earth were to be inhabited only by humans with no other animals present, it would have significant and far-reaching consequences for the planet's ecosystem, human society, and the environment. Here are some potential impacts:

1. Ecosystem Collapse: Animals play crucial roles in ecosystems; they help control populations of plants and other animals, are pollinators, and serve as prey. Without them, ecosystems would become unbalanced, potentially leading to the collapse of many ecological systems.

2. Biodiversity Loss: The loss of all animal species would result in a drastic reduction in biodiversity and may lead to the extinction of numerous plant species that depend on animals for pollination or seed dispersal.

3. Agriculture Impact: Many agricultural practices rely on animals for labor (e.g., plowing fields with oxen), for producing food (e.g., cattle for meat and milk), or for pollination of crops (e.g., bees for fruit trees). The absence of these contributions would necessitate the development of alternative methods of agriculture and possibly result in reduced food production.

4. Environmental Health: Animals help maintain environmental health through processes like nutrient recycling, pest control, and maintaining soil health. Their absence could lead to the accumulation of waste and imbalance in nutrient cycles.

5. Human Health: The disappearance of animals would affect human health directly (through the loss of food sources) and indirectly (by affecting the spread of diseases and the balance of ecosystems). Medical research also often relies on animals for testing therapies and understanding biological mechanisms.

6. Food Chain Disruption: Without animals, the food chain would be significantly disrupted. Humans would need to find new ways to meet their dietary needs, which could include shifting to a more plant-based diet or developing synthetic food sources.

7. Cultural and Emotional Impact: Animals play important roles in human culture, from being companions to featuring in art, literature, and religion. Their absence would have significant emotional and cultural consequences.

8. Economic Effects: Industries such as tourism, clothing, and certain types of cuisine heavily rely on animals. The absence of animals would lead to economic shifts and job losses in these sectors.

9. Biomedical Research: Much of our medical knowledge is based on studies involving animals. Without them, progress in areas such as drug testing, disease modeling, and understanding the basics of biology would be severely hindered.

10. Ethical Considerations: The ethical implications of a world without animals would be profound, including debates about the value of non-human life, the responsibility of humans towards other species, and the moral dimensions of altering ecosystems.

Ultimately, the absence of all animals from the Earth would not only drastically alter ecosystems but would also deeply impact human culture, economy, and society, emphasizing the interconnectedness of all life on our planet.